1.
Weight
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In science and engineering, the weight of an object is usually taken to be the force on the object due to gravity. Weight is a vector whose magnitude, often denoted by an italic letter W, is the product of the m of the object. The unit of measurement for weight is that of force, which in the International System of Units is the newton. For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, in this sense of weight, a body can be weightless only if it is far away from any other mass. Although weight and mass are scientifically distinct quantities, the terms are often confused with other in everyday use. There is also a tradition within Newtonian physics and engineering which sees weight as that which is measured when one uses scales. There the weight is a measure of the magnitude of the force exerted on a body. Typically, in measuring an objects weight, the object is placed on scales at rest with respect to the earth, thus, in a state of free fall, the weight would be zero. In this second sense of weight, terrestrial objects can be weightless, ignoring air resistance, the famous apple falling from the tree, on its way to meet the ground near Isaac Newton, is weightless. Further complications in elucidating the various concepts of weight have to do with the theory of relativity according to gravity is modelled as a consequence of the curvature of spacetime. In the teaching community, a debate has existed for over half a century on how to define weight for their students. The current situation is that a set of concepts co-exist. Discussion of the concepts of heaviness and lightness date back to the ancient Greek philosophers and these were typically viewed as inherent properties of objects. Plato described weight as the tendency of objects to seek their kin. To Aristotle weight and levity represented the tendency to restore the order of the basic elements, air, earth, fire. He ascribed absolute weight to earth and absolute levity to fire, archimedes saw weight as a quality opposed to buoyancy, with the conflict between the two determining if an object sinks or floats. The first operational definition of weight was given by Euclid, who defined weight as, weight is the heaviness or lightness of one thing, compared to another, operational balances had, however, been around much longer. According to Aristotle, weight was the cause of the falling motion of an object
2.
Newton (unit)
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The newton is the International System of Units derived unit of force. It is named after Isaac Newton in recognition of his work on classical mechanics, see below for the conversion factors. One newton is the force needed to one kilogram of mass at the rate of one metre per second squared in direction of the applied force. In 1948, the 9th CGPM resolution 7 adopted the name newton for this force, the MKS system then became the blueprint for todays SI system of units. The newton thus became the unit of force in le Système International dUnités. This SI unit is named after Isaac Newton, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. Newtons second law of motion states that F = ma, where F is the applied, m is the mass of the object receiving the force. The newton is therefore, where the symbols are used for the units, N for newton, kg for kilogram, m for metre. In dimensional analysis, F = M L T2 where F is force, M is mass, L is length, at average gravity on earth, a kilogram mass exerts a force of about 9.8 newtons. An average-sized apple exerts about one newton of force, which we measure as the apples weight, for example, the tractive effort of a Class Y steam train and the thrust of an F100 fighter jet engine are both around 130 kN. One kilonewton,1 kN, is 102.0 kgf,1 kN =102 kg ×9.81 m/s2 So for example, a platform rated at 321 kilonewtons will safely support a 32,100 kilograms load. Specifications in kilonewtons are common in safety specifications for, the values of fasteners, Earth anchors. Working loads in tension and in shear, thrust of rocket engines and launch vehicles clamping forces of the various moulds in injection moulding machines used to manufacture plastic parts
3.
Kilogram
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The kilogram or kilogramme is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype of the Kilogram. The avoirdupois pound, used in both the imperial and US customary systems, is defined as exactly 0.45359237 kg, making one kilogram approximately equal to 2.2046 avoirdupois pounds. Other traditional units of weight and mass around the world are also defined in terms of the kilogram, the gram, 1/1000 of a kilogram, was provisionally defined in 1795 as the mass of one cubic centimeter of water at the melting point of ice. The final kilogram, manufactured as a prototype in 1799 and from which the IPK was derived in 1875, had an equal to the mass of 1 dm3 of water at its maximum density. The kilogram is the only SI base unit with an SI prefix as part of its name and it is also the only SI unit that is still directly defined by an artifact rather than a fundamental physical property that can be reproduced in different laboratories. Three other base units and 17 derived units in the SI system are defined relative to the kilogram, only 8 other units do not require the kilogram in their definition, temperature, time and frequency, length, and angle. At its 2011 meeting, the CGPM agreed in principle that the kilogram should be redefined in terms of the Planck constant, the decision was originally deferred until 2014, in 2014 it was deferred again until the next meeting. There are currently several different proposals for the redefinition, these are described in the Proposed Future Definitions section below, the International Prototype Kilogram is rarely used or handled. In the decree of 1795, the term gramme thus replaced gravet, the French spelling was adopted in the United Kingdom when the word was used for the first time in English in 1797, with the spelling kilogram being adopted in the United States. In the United Kingdom both spellings are used, with kilogram having become by far the more common, UK law regulating the units to be used when trading by weight or measure does not prevent the use of either spelling. In the 19th century the French word kilo, a shortening of kilogramme, was imported into the English language where it has used to mean both kilogram and kilometer. In 1935 this was adopted by the IEC as the Giorgi system, now known as MKS system. In 1948 the CGPM commissioned the CIPM to make recommendations for a practical system of units of measurement. This led to the launch of SI in 1960 and the subsequent publication of the SI Brochure, the kilogram is a unit of mass, a property which corresponds to the common perception of how heavy an object is. Mass is a property, that is, it is related to the tendency of an object at rest to remain at rest, or if in motion to remain in motion at a constant velocity. Accordingly, for astronauts in microgravity, no effort is required to hold objects off the cabin floor, they are weightless. However, since objects in microgravity still retain their mass and inertia, the ratio of the force of gravity on the two objects, measured by the scale, is equal to the ratio of their masses. On April 7,1795, the gram was decreed in France to be the weight of a volume of pure water equal to the cube of the hundredth part of the metre
4.
Uniform Penny Post
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The Uniform Penny Post was a component of the comprehensive reform of the Royal Mail, the UKs official postal service, that took place in the 19th century. The reforms were a government initiative to eradicate the abuse and corruption of the existing service, richard Cobden and John Ramsey McCulloch, both advocates of free trade, attacked the Conservative governments policies of privilege and protection, including their archaic postal system. McCulloch, in 1833, advanced the view that nothing more to facilitate commerce than the safe, speedy. However, Hill did not include a timetable for the introduction of a penny post in his proposal. Nonetheless, Hills 1838 proposal paved the way for the 1840 Act which introduced the Uniform Penny Post. In his proposal, Hill also called for official pre-printed envelopes and adhesive postage stamps as alternative ways of getting the sender to pay for postage and this was a lower rate than before, when the cost of postage was usually more than 4d. The reform did not settle the issue of who paid for the postage, as of 2013 the value of one penny in 1840 ranges from 32p to 4.89, the latter based on mean income. It would appear that the cost to an established semi-skilled man of sending a letter in 1840 can be represented by approximately 1, financially, the penny post scheme was a disaster. More than thirty years elapsed before revenues were back to the pre-1840 level, the real benefits were the encouragement and support that the availability of cheap letterpost communication gave to the development of transport links, education, commerce and social cohesion. Uniform Fourpenny Post Penny Black Postage stamps and postal history of Great Britain Ashurst, facts and reasons in support of Mr. Rowland Hills plan for a universal penny postage. Penny Postage Centenary, An account of Rowland Hills great reform of 1840, london, The Postal History Society,1940 144p. Grimwood-Taylor, James L. Derby, Published for the author by Cavendish Philatelic Auctions Ltd.1990 ISBN 0-9515626-0-6, london, Charles Knight and Company,1844 84p. Great Britain, The Development and Introduction of Uniform Penny Postage, gerrards Cross, the author,2006 15p. Uniform Penny Post, Handstruck Paid Postage Stamps of England and Wales 1840-1853, sutton Coldfield, GBPS,2013 ISBN 978-0-907630-24-1, 32p
5.
Spring scale
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A spring scale or spring balance or newton meter is a type of weighing scale. It consists of spring fixed at one end with a hook to attach an object at the other and it works by Hookes Law, which states that the force needed to extend a spring is proportional to the distance that spring is extended from its rest position. Therefore, the markings on the spring balance are equally spaced. A spring scale can not measure mass, only weight, also, the spring in the scale can permanently stretch with repeated use. A spring scale will only read correctly in a frame of reference where the acceleration in the axis is constant. This can be shown by taking a spring scale into an elevator, if two or more spring balances are hung one below the other in series, each of the scales will read approximately the same, the full weight of the body hung on the lower scale. The scale on top would read slightly heavier due to supporting the weight of the lower scale itself. Spring balances come in different sizes, generally, small scales that measure newtons will have a less firm spring than larger ones that measure tens, hundreds or thousands of newtons or even more depending on the scale of newtons used. The largest spring scale ranged in measurement from 5000-8000 newtons, a spring balance may be labeled in both units of force and mass. Strictly speaking, only the values are correctly labeled. Main uses of spring balances are industrial, especially related to weighing heavy loads such as trucks, storage silos and they are also common in science education as basic accelerators. They are used when the accuracy afforded by other types of scales can be sacrificed for simplicity, cheapness, a spring balance measures the weight of an object by opposing the force of gravity acting with the force of an extended spring. The first spring balance in Britain was made around 1770 by Richard Salter of Bilston and he and his nephews John & George founded the firm of George Salter & Co. still notable makers of scales and balances, who in 1838 patented the spring balance. They also applied the same spring balance principle to steam locomotive safety valves, weighing scale Media related to spring balance at Wikimedia Commons Media related to spring scales at Wikimedia Commons
6.
Spring (device)
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A spring is an elastic object used to store mechanical energy. Springs are usually out of spring steel. There are a number of spring designs, in everyday usage the term often refers to coil springs. When a spring is compressed or stretched from its resting position, the rate or spring constant of a spring is the change in the force it exerts, divided by the change in deflection of the spring. That is, it is the gradient of the force versus deflection curve, an extension or compression springs rate is expressed in units of force divided by distance, for example lbf/in or N/m. A torsion spring is a spring that works by twisting, when it is twisted about its axis by an angle, a torsion springs rate is in units of torque divided by angle, such as N·m/rad or ft·lbf/degree. The inverse of spring rate is compliance, that is, if a spring has a rate of 10 N/mm, the stiffness of springs in parallel is additive, as is the compliance of springs in series. Springs are made from a variety of materials, the most common being spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel, some non-ferrous metals are also used including phosphor bronze and titanium for parts requiring corrosion resistance and beryllium copper for springs carrying electrical current. Simple non-coiled springs were used throughout history, e. g. the bow. In the Bronze Age more sophisticated spring devices were used, as shown by the spread of tweezers in many cultures, coiled springs appeared early in the 15th century, in door locks. The first spring powered-clocks appeared in that century and evolved into the first large watches by the 16th century, in 1676 British physicist Robert Hooke discovered Hookes law which states that the force a spring exerts is proportional to its extension. Compression spring – is designed to operate with a compression load, flat spring – this type is made of a flat spring steel. Machined spring – this type of spring is manufactured by machining bar stock with a lathe and/or milling operation rather than a coiling operation, since it is machined, the spring may incorporate features in addition to the elastic element. Machined springs can be made in the load cases of compression/extension, torsion. Serpentine spring - a zig-zag of thick wire - often used in modern upholstery/furniture, the most common types of spring are, Cantilever spring – a spring which is fixed only at one end. Coil spring or helical spring – a spring is of two types, Tension or extension springs are designed to become longer under load and their turns are normally touching in the unloaded position, and they have a hook, eye or some other means of attachment at each end. Compression springs are designed to become shorter when loaded and their turns are not touching in the unloaded position, and they need no attachment points
7.
Torque
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Torque, moment, or moment of force is rotational force. Just as a force is a push or a pull. Loosely speaking, torque is a measure of the force on an object such as a bolt or a flywheel. For example, pushing or pulling the handle of a wrench connected to a nut or bolt produces a torque that loosens or tightens the nut or bolt, the symbol for torque is typically τ, the lowercase Greek letter tau. When it is called moment of force, it is denoted by M. The SI unit for torque is the newton metre, for more on the units of torque, see Units. This article follows US physics terminology in its use of the word torque, in the UK and in US mechanical engineering, this is called moment of force, usually shortened to moment. In US physics and UK physics terminology these terms are interchangeable, unlike in US mechanical engineering, Torque is defined mathematically as the rate of change of angular momentum of an object. The definition of states that one or both of the angular velocity or the moment of inertia of an object are changing. Moment is the term used for the tendency of one or more applied forces to rotate an object about an axis. For example, a force applied to a shaft causing acceleration, such as a drill bit accelerating from rest. By contrast, a force on a beam produces a moment, but since the angular momentum of the beam is not changing. Similarly with any force couple on an object that has no change to its angular momentum and this article follows the US physics terminology by calling all moments by the term torque, whether or not they cause the angular momentum of an object to change. The concept of torque, also called moment or couple, originated with the studies of Archimedes on levers, the term torque was apparently introduced into English scientific literature by James Thomson, the brother of Lord Kelvin, in 1884. A force applied at an angle to a lever multiplied by its distance from the levers fulcrum is its torque. A force of three newtons applied two metres from the fulcrum, for example, exerts the same torque as a force of one newton applied six metres from the fulcrum. More generally, the torque on a particle can be defined as the product, τ = r × F, where r is the particles position vector relative to the fulcrum. Alternatively, τ = r F ⊥, where F⊥ is the amount of force directed perpendicularly to the position of the particle, any force directed parallel to the particles position vector does not produce a torque
8.
Lever
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A lever is a machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a body capable of rotating on a point on itself. On the basis of the location of fulcrum, load and effort and it is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide an output force. The ratio of the force to the input force is the mechanical advantage of the lever. The word lever entered English about 1300 from Old French, in which the word was levier and this sprang from the stem of the verb lever, meaning to raise. The verb, in turn, goes back to the Latin levare, itself from the adjective levis, the words primary origin is the Proto-Indo-European stem legwh-, meaning light, easy or nimble, among other things. The PIE stem also gave rise to the English word light, the earliest remaining writings regarding levers date from the 3rd century BC and were provided by Archimedes. Give me a place to stand, and I shall move the Earth with it is a remark of Archimedes who formally stated the correct mathematical principle of levers. The distance required to do this might be exemplified in astronomical terms as the distance to the Circinus galaxy - about 9 million light years. It is assumed that in ancient Egypt, constructors used the lever to move, a lever is a beam connected to ground by a hinge, or pivot, called a fulcrum. The ideal lever does not dissipate or store energy, which there is no friction in the hinge or bending in the beam. This is known as the law of the lever, the mechanical advantage of a lever can be determined by considering the balance of moments or torque, T, about the fulcrum. T1 = F1 a, T2 = F2 b where F1 is the force to the lever. The distances a and b are the distances between the forces and the fulcrum. Since the moments of torque must be balanced, T1 = T2, the mechanical advantage of the lever is the ratio of output force to input force, M A = F2 F1 = a b. Levers are classified by the positions of the fulcrum, effort. It is common to call the force the effort and the output force the load or the resistance
9.
Force
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In physics, a force is any interaction that, when unopposed, will change the motion of an object. In other words, a force can cause an object with mass to change its velocity, force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity and it is measured in the SI unit of newtons and represented by the symbol F. The original form of Newtons second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. In an extended body, each part usually applies forces on the adjacent parts, such internal mechanical stresses cause no accelation of that body as the forces balance one another. Pressure, the distribution of small forces applied over an area of a body, is a simple type of stress that if unbalanced can cause the body to accelerate. Stress usually causes deformation of materials, or flow in fluids. In part this was due to an understanding of the sometimes non-obvious force of friction. A fundamental error was the belief that a force is required to maintain motion, most of the previous misunderstandings about motion and force were eventually corrected by Galileo Galilei and Sir Isaac Newton. With his mathematical insight, Sir Isaac Newton formulated laws of motion that were not improved-on for nearly three hundred years, the Standard Model predicts that exchanged particles called gauge bosons are the fundamental means by which forces are emitted and absorbed. Only four main interactions are known, in order of decreasing strength, they are, strong, electromagnetic, weak, high-energy particle physics observations made during the 1970s and 1980s confirmed that the weak and electromagnetic forces are expressions of a more fundamental electroweak interaction. Since antiquity the concept of force has been recognized as integral to the functioning of each of the simple machines. The mechanical advantage given by a machine allowed for less force to be used in exchange for that force acting over a greater distance for the same amount of work. Analysis of the characteristics of forces ultimately culminated in the work of Archimedes who was famous for formulating a treatment of buoyant forces inherent in fluids. Aristotle provided a discussion of the concept of a force as an integral part of Aristotelian cosmology. In Aristotles view, the sphere contained four elements that come to rest at different natural places therein. Aristotle believed that objects on Earth, those composed mostly of the elements earth and water, to be in their natural place on the ground. He distinguished between the tendency of objects to find their natural place, which led to natural motion, and unnatural or forced motion
10.
Tension (physics)
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Tension is the opposite of compression. At the atomic level, when atoms or molecules are pulled apart each other and gain potential energy with a restoring force still existing. Each end of a string or rod under such tension will pull on the object it is attached to, to restore the string/rod to its relaxed length. In physics, tension, as a force, as an action-reaction pair of forces. The ends of a string or other object transmitting tension will exert forces on the objects to which the string or rod is connected and these forces due to tension are also called passive forces. Tension in a string is a scalar quantity. A string or rope is often idealized as one dimension, having length but being massless with zero cross section. If there are no bends in the string, as occur with vibrations or pulleys, then tension is a constant along the string, by Newtons Third Law, these are the same forces exerted on the ends of the string by the objects to which the ends are attached. If the string curves around one or more pulleys, it still have constant tension along its length in the idealized situation that the pulleys are massless and frictionless. A vibrating string vibrates with a set of frequencies that depend on the strings tension and these frequencies can be derived from Newtons laws of motion. Each microscopic segment of the string pulls on and is pulled upon by its neighboring segments, tension = τ where x is the position along the string. If the string has curvature, then the two pulls on a segment by its two neighbors will not add to zero, and there will be a net force on that segment of the string, causing an acceleration. With solutions that include the various harmonics on a stringed instrument, tension is also used to describe the force exerted by the ends of a three-dimensional, continuous material such as a rod or truss member. Such a rod elongates under tension, a system is in equilibrium when the sum of all forces is zero. ∑ F → =0 For example, consider a system consisting of an object that is being lowered vertically by a string with tension, T, at a constant velocity. ∑ F → = T → + m g → =0 A system has a net force when a force is exerted on it. Acceleration and net force always exist together, ∑ F → ≠0 For example, consider the same system as above but suppose the object is now being lowered with an increasing velocity downwards therefore there exists a net force somewhere in the system. In this case, negative acceleration would indicate that | m g | > | T |
11.
Gravity
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Gravity, or gravitation, is a natural phenomenon by which all things with mass are brought toward one another, including planets, stars and galaxies. Since energy and mass are equivalent, all forms of energy, including light, on Earth, gravity gives weight to physical objects and causes the ocean tides. Gravity has a range, although its effects become increasingly weaker on farther objects. The most extreme example of this curvature of spacetime is a hole, from which nothing can escape once past its event horizon. More gravity results in time dilation, where time lapses more slowly at a lower gravitational potential. Gravity is the weakest of the four fundamental interactions of nature, the gravitational attraction is approximately 1038 times weaker than the strong force,1036 times weaker than the electromagnetic force and 1029 times weaker than the weak force. As a consequence, gravity has an influence on the behavior of subatomic particles. On the other hand, gravity is the dominant interaction at the macroscopic scale, for this reason, in part, pursuit of a theory of everything, the merging of the general theory of relativity and quantum mechanics into quantum gravity, has become an area of research. While the modern European thinkers are credited with development of gravitational theory, some of the earliest descriptions came from early mathematician-astronomers, such as Aryabhata, who had identified the force of gravity to explain why objects do not fall out when the Earth rotates. Later, the works of Brahmagupta referred to the presence of force, described it as an attractive force. Modern work on gravitational theory began with the work of Galileo Galilei in the late 16th and this was a major departure from Aristotles belief that heavier objects have a higher gravitational acceleration. Galileo postulated air resistance as the reason that objects with less mass may fall slower in an atmosphere, galileos work set the stage for the formulation of Newtons theory of gravity. In 1687, English mathematician Sir Isaac Newton published Principia, which hypothesizes the inverse-square law of universal gravitation. Newtons theory enjoyed its greatest success when it was used to predict the existence of Neptune based on motions of Uranus that could not be accounted for by the actions of the other planets. Calculations by both John Couch Adams and Urbain Le Verrier predicted the position of the planet. A discrepancy in Mercurys orbit pointed out flaws in Newtons theory, the issue was resolved in 1915 by Albert Einsteins new theory of general relativity, which accounted for the small discrepancy in Mercurys orbit. The simplest way to test the equivalence principle is to drop two objects of different masses or compositions in a vacuum and see whether they hit the ground at the same time. Such experiments demonstrate that all objects fall at the rate when other forces are negligible
12.
Calibration
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Calibration in measurement technology and metrology is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known accuracy, strictly, the term calibration means just the act of comparison, and does not include any subsequent adjustment. The calibration standard is normally traceable to a national standard held by a National Metrological Institute and this definition states that the calibration process is purely a comparison, but introduces the concept of Measurement uncertainty in relating the accuracies of the device under test and the standard. The increasing need for accuracy and uncertainty and the need to have consistent. In many countries a National Metrology Institute will exist which will maintain primary standards of measurement which will be used to provide traceability to customers instruments by calibration. The NMI supports the metrological infrastructure in that country by establishing an unbroken chain, examples of National Metrology Institutes are NPL in the UK, NIST in the United States, PTB in Germany and many others. This may be done by national standards laboratories operated by the government or by private firms offering metrology services, quality management systems call for an effective metrology system which includes formal, periodic, and documented calibration of all measuring instruments. ISO9000 and ISO17025 standards require that these actions are to a high level. To communicate the quality of a calibration the calibration value is often accompanied by a traceable uncertainty statement to a confidence level. This is evaluated through careful uncertainty analysis, some times a DFS is required to operate machinery in a degraded state. Whenever this does happen, it must be in writing and authorized by a manager with the assistance of a calibration technician. Measuring devices and instruments are categorized according to the quantities they are designed to measure. These vary internationally, e. g. NIST 150-2G in the U. S. the standard instrument for each test device varies accordingly, e. g. a dead weight tester for pressure gauge calibration and a dry block temperature tester for temperature gauge calibration. g. This is the perception of the instruments end-user, however, very few instruments can be adjusted to exactly match the standards they are compared to. For the vast majority of calibrations, the process is actually the comparison of an unknown to a known. The calibration process begins with the design of the instrument that needs to be calibrated. The design has to be able to hold a calibration through its calibration interval, in other words, the design has to be capable of measurements that are within engineering tolerance when used within the stated environmental conditions over some reasonable period of time. Having a design with these characteristics increases the likelihood of the measuring instruments performing as expected
13.
Grocery store
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A grocery store is a retail store that primarily sells food. A grocer is a seller of food. Grocery stores often offer non-perishable food that is packaged in cans, bottles and boxes, with also having fresh produce, butchers, delis. Large grocery stores that stock significant amounts of products, such as clothing. Some large supermarkets also include a pharmacy, and customer service, redemption, in the United States, Canada, and United Kingdom, supermarkets and convenience stores are sometimes described as grocery businesses, or simply grocers. Some grocery stores form the centerpiece of a complex that includes other facilities, such as gas stations. This setup is especially common in the United Kingdom, with chains such as Tesco. Some groceries specialize in the foods of a nationality or culture, such as Italian, Polish. These stores are known as ethnic markets and may serve as gathering places for immigrants. In many cases, the range of products carried by larger supermarkets has reduced the need for such speciality stores. The variety and availability of food is no longer restricted by the diversity of locally grown food or the limitations of the growing season. Beginning as early as the 14th century, a grocer was a dealer in dry goods such as spices, peppers, sugar. These items were bought in bulk, hence the term grocer from the French grossier meaning wholesaler, as increasing numbers of staple foodstuffs became available in cans and other less-perishable packaging, the trade expanded its province. Today, grocers deal in a range of staple food-stuffs including such perishables as meats, produce. These trading posts evolved into larger retail businesses known as general stores and these facilities generally dealt only in dry goods such as flour, dry beans, baking soda, and canned foods. Many rural areas still contain general stores that sell goods ranging from cigars to imported napkins, traditionally, general stores have offered credit to their customers, a system of payment that works on trust rather than modern credit cards. This allowed farm families to buy staples until their harvest could be sold, the first self-service grocery store, Piggly Wiggly, was opened in 1916 in Memphis, Tennessee by Clarence Saunders, an inventor and entrepreneur. The early supermarkets began as chains of grocers shops, a small grocery store may also compete by locating in a mixed commercial-residential area close to, and convenient for, its customers
14.
Hooke's law
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Hookes law is a principle of physics that states that the force needed to extend or compress a spring by some distance X is proportional to that distance. That is, F = kX, where k is a constant factor characteristic of the spring, its stiffness, the law is named after 17th-century British physicist Robert Hooke. He first stated the law in 1676 as a Latin anagram and he published the solution of his anagram in 1678 as, ut tensio, sic vis. Hooke states in the 1678 work that he was aware of the law already in 1660, an elastic body or material for which this equation can be assumed is said to be linear-elastic or Hookean. Hookes law is only a linear approximation to the real response of springs. Many materials will deviate from Hookes law well before those elastic limits are reached. On the other hand, Hookes law is an approximation for most solid bodies, as long as the forces. For this reason, Hookes law is used in all branches of science and engineering. It is also the principle behind the spring scale, the manometer. The modern theory of elasticity generalizes Hookes law to say that the strain of an object or material is proportional to the stress applied to it. In this general form, Hookes law makes it possible to deduce the relation between strain and stress for complex objects in terms of properties of the materials it is made of. Consider a simple helical spring that has one end attached to some fixed object, suppose that the spring has reached a state of equilibrium, where its length is not changing anymore. Let X be the amount by which the end of the spring was displaced from its relaxed position. Hookes law states that F = k X or, equivalently, X = F k where k is a real number. Moreover, the formula holds when the spring is compressed. According to this formula, the graph of the applied force F as a function of the displacement X will be a line passing through the origin. Hookes law for a spring is often stated under the convention that F is the force exerted by the spring on whatever is pulling its free end. In that case, the equation becomes F = − k X since the direction of the force is opposite to that of the displacement
15.
Pressure measurement
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Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure in a unit are called pressure gauges or vacuum gauges. A manometer is an example as it uses a column of liquid to both measure and indicate pressure. Likewise the widely used Bourdon gauge is a device which both measures and indicates, and is probably the best known type of gauge. A vacuum gauge is a pressure gauge used to measure the pressures lower than the ambient atmospheric pressure. Other methods of pressure measurement involve sensors which can transmit the pressure reading to an indicator or control system. Everyday pressure measurements, such as for vehicle tire pressure, are made relative to ambient air pressure. In other cases measurements are made relative to a vacuum or to other specific reference. Gauge pressure is zero-referenced against ambient air pressure, so it is equal to absolute pressure minus atmospheric pressure, to distinguish a negative pressure, the value may be appended with the word vacuum or the gauge may be labeled a vacuum gauge. These are further divided into two subcategories, high and low vacuum, the applicable pressure ranges of many of the techniques used to measure vacuums have an overlap. Hence, by combining different types of gauge, it is possible to measure system pressure continuously from 10 mbar down to 10−11 mbar. Differential pressure is the difference in pressure between two points, the zero reference in use is usually implied by context, and these words are added only when clarification is needed. Tire pressure and blood pressure are gauge pressures by convention, while atmospheric pressures, deep vacuum pressures, for most working fluids where a fluid exists in a closed system, gauge pressure measurement prevails. Pressure instruments connected to the system will indicate pressures relative to the current atmospheric pressure, the situation changes when extreme vacuum pressures are measured, absolute pressures are typically used instead. Differential pressures are used in industrial process systems. Differential pressure gauges have two ports, each connected to one of the volumes whose pressure is to be monitored. Moderate vacuum pressure readings can be ambiguous without the proper context, thus a vacuum of 26 inHg gauge is equivalent to an absolute pressure of 30 inHg −26 inHg =4 inHg. Atmospheric pressure is typically about 100 kPa at sea level, but is variable with altitude, if the absolute pressure of a fluid stays constant, the gauge pressure of the same fluid will vary as atmospheric pressure changes
16.
Strain gauge
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A strain gauge is a device used to measure strain on an object. Invented by Edward E. Simmons and Arthur C, ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable adhesive, as the object is deformed, the foil is deformed, causing its electrical resistance to change. This resistance change, usually measured using a Wheatstone bridge, is related to the strain by the quantity known as the gauge factor, a strain gauge takes advantage of the physical property of electrical conductance and its dependence on the conductors geometry. Conversely, when a conductor is compressed such that it does not buckle, it will broaden and shorten, from the measured electrical resistance of the strain gauge, the amount of induced stress may be inferred. The gauge factor G F is defined as, G F = Δ R / R G ϵ where Δ R is the change in resistance caused by strain, R G is the resistance of the undeformed gauge, and ϵ is strain. For common metallic foil gauges, the factor is usually a little over 2. Foil gauges typically have active areas of about 2–10 mm² in size, with careful installation, the correct gauge, and the correct adhesive, strains up to at least 10% can be measured. An excitation voltage is applied to input leads of the network. Typical input voltages are 5 V or 12 V and typical output readings are in millivolts, foil strain gauges are used in many situations. Different applications place different requirements on the gauge, in most cases the orientation of the strain gauge is significant. Strain gauges are attached to the substrate with a special glue, the type of glue depends on the required lifetime of the measurement system. For short term measurements cyanoacrylate glue is appropriate, for long lasting installation epoxy glue is required, usually epoxy glue requires high temperature curing. The preparation of the surface where the gauge is to be glued is of the utmost importance. If these steps are not followed the strain gauge binding to the surface may be unreliable and unpredictable measurement errors may be generated, strain gauge based technology is utilized commonly in the manufacture of pressure sensors. The gauges used in pressure sensors themselves are made from silicon, polysilicon, metal film, thick film. Variations in temperature will cause a multitude of effects, the object will change in size by thermal expansion, which will be detected as a strain by the gauge. Resistance of the gauge will change, and resistance of the wires will change
17.
Truck scale
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A Truck scale, weighbridge or railroad scale is a large set of scales, usually mounted permanently on a concrete foundation, that is used to weigh entire rail or road vehicles and their contents. By weighing the vehicle both empty and when loaded, the load carried by the vehicle can be calculated, the key component that uses a weighbridge in order to make the weigh measurement is load cells. Commercial scales have to be National Type Evaluation Program approved or certified.1, NTEP approved scales are generally considered those scales which are intended by the manufacturer for use in commercial applications where products are sold by weight. NTEP Approved is also known as Legal for Trade or complies with Handbook 44 and they are typically built from steel or concrete and by nature are extremely robust. In earlier versions the bridge is installed over a pit that contains levers that ultimately connect to a balance mechanism. The most complex portion of this type is the arrangement of levers underneath the weighbridge since the response of the scale must be independent of the distribution of the load, modern devices use multiple load cells that connect to an electronic equipment to totalize the sensor inputs. In either type of semi-permanent scale the weight readings are typically recorded in a hut or office. Many weighbridges are now linked to a PC which runs truck scale software capable of printing tickets, Truck scales can be used for two main purposes, Selling or charging by weight over the bridge Check weighing both axle weights and gross vehicle weights. This helps to stop axle overloading and possible heavy fines, since the weight of the vehicle carrying the goods is known they are a quick and easy way to measure the flow of bulk goods in and out of different locations. Similar to the full size truck scale these systems can be pit mounted with the weighing surface flush to the level of the roadway or surface mounted, for many uses weighbridges have been largely supplanted by simple and thin electronic weigh cells, over which a vehicle is slowly driven. A computer records the output of the cell and accumulates the total vehicle weight, the former two limits ensure the safety of bridges while the latter protects the road surface. Portable truck scales can also be found in use around the world, a portable truck scale will have lower frame work that can be placed on non-typical surfaces such as dirt. These scales retain the level of accuracy as a pit-type scale. The first portable truck scale record in the US was units operated by the Weight Patrol of the Los Angeles Motor Patrol in 1929, four such weighing units were used with one under each of the trucks wheels. Each unit could record up to 15,000 pounds, on-board scale Scale test car Weighing scale Weigh lock compression Load Cell
18.
Bakery
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A bakery is an establishment that produces and sells flour-based food baked in an oven such as bread, cookies, cakes, pastries, and pies. Some retail bakeries are also cafés, serving coffee and tea to customers who wish to consume the baked goods on the premises, baked goods have been around for thousands of years. The art of baking was developed early during the Roman Empire and it was a highly famous art as Roman citizens loved baked goods and demanded for them frequently for important occasions such as feasts and weddings etc. Due to the fame and desire that the art of baking received, around 300 BC, baking was introduced as an occupation, the bakers began to prepare bread at home in an oven, using mills to grind grain into the flour for their breads. The oncoming demand for baked goods vigorously continued and the first bakers guild was established in 168 BC in Rome and this drastic appeal for baked goods promoted baking all throughout Europe and expanded into the eastern parts of Asia. Bakers started baking breads and goods at home and selling out on the streets. This trend became common and soon, baked products were getting sold in streets of Rome, Germany, London and this resulted in a system of delivering the goods to households, as the demand for baked breads and goods significantly increased. This provoked the bakers to establish a place people could purchase baked goods for themselves. Therefore, in Paris, the first open-air bakery of baked goods was developed and since then, bakeries became a place to purchase delicious goods. By the colonial era, bakeries were commonly viewed as places to gather, world War II directly affected bread industries in the UK. Baking schools closed during this time so when the war did eventually end there was an absence of skilled bakers and this resulted in new methods being developed to satisfy the world’s desire for bread. Methods like, adding chemicals to dough, premixes and specialised machinery, unfortunately these old methods of baking were almost completely eradicated when these new methods were introduced and became industrialised. The old methods were seen as unnecessary and financially unsound, during this period there were not many traditional bakeries left, some bakeries provide services for special occasions or for people who have allergies or sensitivities to certain foods. Bakeries can provide a range of cakes designs such as sheet cakes, layer cakes, tiered cakes. Grocery stores and supermarkets, in countries, sell prepackaged or pre-sliced bread, cakes. They can also offer in-store baking and basic cake decoration
19.
Delicatessen
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A delicatessen or deli is a retail establishment that sells a selection of unusual or foreign prepared foods. Delicatessens originated in Germany during the 1700s and spread to the United States in the mid-1800s, European immigrants to the United States, especially Ashkenazi Jews, popularized the delicatessen in American culture beginning in the late 1800s. Delicatessen is a German loanword which first appeared in English in 1889 and is the plural of Delikatesse, in German it was originally a French loanword, délicatesse, meaning delicious things. Its root word is the Latin adjective delicatus, meaning giving pleasure, delightful, the first Americanized short version of this word, deli, came into existence c. 1954. The German food company Dallmayr is credited with being the first delicatessen created, in 1700, it became the first store to import bananas, mangoes, and plums to the German population from faraway places such as the Canary Islands and China. Over 300 years later, it remains the largest business of its kind in Europe, the first delicatessens to appear in the United States were in New York City in the mid-1800s, with the first known use of this word occurring in 1885. These catered to the German immigrant population living there, as the German-Jewish population increased in New York City during the mid- to late 1800s, kosher delicatessens began to open, the first was founded in 1889. In the United States, by the late 20th to early 21st centuries, supermarkets, local economy stores, and fast food outlets began using the word to describe sections of their stores. The decline of the deli as an independent retail establishment was most noted in New York City, from a high in the 1930s of about 1,500 Jewish delicatessens, in most of Australia, the term delicatessen retains its European meaning. Large supermarket chains often have a department, and independent delicatessens exist throughout the country. Both types of deli offer a variety of cured meats, sausages, pickled vegetables, dips, breads, Deli also denotes a small convenience store or milk bar in Western and South Australia, and some businesses use deli as part of their business name. Traditional delicatessens also exist in these states, with continental delicatessen sometimes used to indicate the European version, in Canada, both meanings of delicatessen are used. In Europe delicatessen means high-quality, expensive foods and stores, in German-speaking countries a common synonym is Feinkost, and shops which sell it are called Feinkostläden. Department stores often have a Delikatessenabteilung, European delicatessens include Fauchon in Paris, Dallmayr in Munich, Harrods and Fortnum & Mason in London, and Peck in Milan. Although U. S. -style delicatessens are also found in Europe, in Russia, shops and supermarket sections approximating US-style delis are called kulinariya and offer salads and main courses. Delicate meats and cheeses, cold-cut and sliced hot, are sold in a separate section, the Eliseevsky food store in central Moscow, with its fin de siècle decor, is similar to a European delicatessen. From the Tsarist era, it was preserved by the Soviets as an outlet for difficult-to-obtain Russian delicacies, delicatessens may also provide foods from other countries and cultures which is not readily available in local food stores. In Italy, the deli can be called gastronomia, negozio di specialità gastronomiche, in France it is nowadays known as a traiteur or épicerie fine
20.
Seafood
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Seafood is any form of sea life regarded as food by humans. Seafood prominently includes fish and shellfish, shellfish include various species of molluscs, crustaceans, and echinoderms. Historically, sea mammals such as whales and dolphins have been consumed as food, edible sea plants, such as some seaweeds and microalgae, are widely eaten as seafood around the world, especially in Asia. In North America, although not generally in the United Kingdom, for the sake of completeness, this article includes all edible aquatic life. The harvesting of seafood is usually known as fishing or hunting. Seafood is often distinguished from meat, although it is still animal and is excluded in a vegetarian diet. Seafood is an important source of protein in many diets around the world, most of the seafood harvest is consumed by humans, but a significant proportion is used as fish food to farm other fish or rear farm animals. Some seafoods are used as food for other plants, in these ways, seafoods are indirectly used to produce further food for human consumption. Products, such as oil and spirulina tablets are also extracted from seafoods. Some seafood is feed to fish, or used to feed domestic pets, such as cats. The harvesting, processing, and consuming of seafoods are ancient practices with archaeological evidence dating back well into the Paleolithic, isotopic analysis of the skeletal remains of Tianyuan man, a 40, 000-year-old modern human from eastern Asia, has shown that he regularly consumed freshwater fish. Archaeology features such as middens, discarded fish bones and cave paintings show that sea foods were important for survival. During this period, most people lived a lifestyle and were, of necessity. However, where there are examples of permanent settlements such as those at Lepenski Vir. The ancient river Nile was full of fish, fresh and dried fish were a food for much of the population. The Egyptians had implements and methods for fishing and these are illustrated in scenes, drawings. Some representations hint at fishing being pursued as a pastime, fishing scenes are rarely represented in ancient Greek culture, a reflection of the low social status of fishing. However, Oppian of Corycus, a Greek author wrote a treatise on sea fishing
21.
Meat
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Meat is animal flesh that is eaten as food. Humans have hunted and killed animals for meat since prehistoric times, the advent of civilization allowed the domestication of animals such as chickens, sheep, pigs and cattle. This eventually led to their use in production on an industrial scale with the aid of slaughterhouses. Meat is mainly composed of water, protein, and fat and it is edible raw, but is normally eaten after it has been cooked and seasoned or processed in a variety of ways. Unprocessed meat will spoil or rot within hours or days as a result of infection with and decomposition by bacteria, most often, meat refers to skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as offal. The word meat comes from the Old English word mete, which referred to food in general, the term is related to mad in Danish, mat in Swedish and Norwegian, and matur in Icelandic and Faroese, which also mean food. The word mete also exists in Old Frisian to denote important food, differentiating it from swiets, paleontological evidence suggests that meat constituted a substantial proportion of the diet of even the earliest humans. Early hunter-gatherers depended on the hunting of large animals such as bison. Several breeds of sheep were established in ancient Mesopotamia and Egypt by 3500–3000 BC, today, more than 200 sheep-breeds exist. Cattle were domesticated in Mesopotamia after settled agriculture was established about 5000 BC, modern domesticated cattle fall into the groups Bos taurus and Bos indicus, both descended from the now-extinct aurochs. The breeding of cattle, cattle optimized for meat production as opposed to animals best suited for draught or dairy purposes. Domestic pigs, which are descended from boars, are known to have existed about 2500 BC in modern-day Hungary and in Troy, earlier pottery from Jericho. Pork sausages and hams were of commercial importance in Greco-Roman times. Pigs continue to be bred intensively as they are being optimized to produce meat best suited for meat products. Other animals are or have raised or hunted for their flesh. The type of meat consumed varies much between different cultures, changes over time, depending on such as tradition and the availability of the animals. The amount and kind of meat consumed also varies by income, horses are commonly eaten in France, Italy, Germany and Japan, among other countries. Horses and other mammals such as reindeer were hunted during the late Paleolithic in western Europe
22.
Produce
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Produce is a generalized term for a group of farm-produced crops and goods, including fruits and vegetables – meats, grains, oats, etc. are also sometimes considered produce. More specifically, the term often implies that the products are fresh. In supermarkets the term is used to refer to the section where fruit. Produce is the product sold by greengrocers, farmers markets. The term produce is used in the U. S. but is not typically used outside the agricultural sector in other English-speaking countries. In parts of the world including the U. S. produce is marked with small stickers bearing price look-up codes and these four- or five-digit codes are a standardized system intended to aid checkout and inventory control in produce markets. Although in most parts of the world forms of produce are available year-round. The seasonality of produce depends on variables such as climate and weather. Below is a general list of produce seasonality for north of and south of the tropics, including Canada, spring fruits are apricots, strawberries, cherries. Spring vegetables are peas and more delicate cabbages including mustard greens, baby lettuce, baby spinach, also in season are artichoke, asparagus, avocado, new potatoes, rhubarb. Summer fruits include some berries and stone fruit as well as melons, summer vegetables include beets, corn, cucumber, eggplant, green beans, tomatoes and zucchini. Autumn fruits includes apples, cranberries, grapes, figs, pears, autumn vegetables include many cultivars of wild cabbage. Root vegetables and winter squash are also in season, corn is in season and peas, seasonal in spring, are also seasonal in late autumn. Winter fruits include citrus and pomegranates, also seasonal in winter are some root vegetables as well as winter squash. Some produce, such as onions, lettuce, spinach and strawberries are seasonal year-round in subtropical climates, vegetables are optimally stored between 0° and 4. 4° Celsius to reduce respiration. Generally, vegetables should be stored at a high humidity, but cucubits and onions prefer dry, raw sprouts are among the most risky produce. Rinsing is a way to reduce the bacteria count on produce. Wastewater can be a source of contamination, due to contamination of water with fecal matter with salmonella or other bacteria, after Denmark eliminated salmonella in its chickens, attention has turned to vegetables as a source of illness
23.
Radio-frequency identification
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Radio-frequency identification uses electromagnetic fields to automatically identify and track tags attached to objects. The tags contain electronically stored information, Passive tags collect energy from a nearby RFID readers interrogating radio waves. Active tags have a power source such as a battery. Unlike a barcode, the tag need not be within the line of sight of the reader, RFID is one method for Automatic Identification and Data Capture. These concerns resulted in standard specifications development addressing privacy and security issues, ISO/IEC18000 and ISO/IEC29167 use on-chip cryptography methods for untraceability, tag and reader authentication, and over-the-air privacy. ISO/IEC20248 specifies a digital data structure for RFID and barcodes providing data, source. This work is done within ISO/IEC JTC 1/SC31 Automatic identification, in 2014, the world RFID market is worth US$8.89 billion, up from US$7.77 billion in 2013 and US$6.96 billion in 2012. This includes tags, readers, and software/services for RFID cards, labels, fobs, the market value is expected to rise to US$18.68 billion by 2026. In 1945, Léon Theremin invented a tool for the Soviet Union which retransmitted incident radio waves with the audio information. Sound waves vibrated a diaphragm which slightly altered the shape of the resonator, similar technology, such as the IFF transponder, was routinely used by the allies and Germany in World War II to identify aircraft as friend or foe. Transponders are still used by most powered aircraft to this day, another early work exploring RFID is the landmark 1948 paper by Harry Stockman. Considerable research and development work has to be done before the basic problems in reflected-power communication are solved. Mario Cardullos device, patented on January 23,1973, was the first true ancestor of modern RFID, the basic Cardullo patent covers the use of RF, sound and light as transmission media. The original business plan presented to investors in 1969 showed uses in transportation, banking, security and medical. An early demonstration of reflected power RFID tags, both passive and semi-passive, was performed by Steven Depp, Alfred Koelle, and Robert Frayman at the Los Alamos National Laboratory in 1973, the portable system operated at 915 MHz and used 12-bit tags. This technique is used by the majority of todays UHFID and microwave RFID tags, the first patent to be associated with the abbreviation RFID was granted to Charles Walton in 1983. A radio-frequency identification system uses tags, or labels attached to the objects to be identified, two-way radio transmitter-receivers called interrogators or readers send a signal to the tag and read its response. RFID tags can be passive, active or battery-assisted passive
24.
International Organization of Legal Metrology
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The organisation has no legal authority to impose solutions on its members, but its recommendations are often used by member states as part of their own domestic law. As of October 2013,59 countries had signed up as full members, between them, the OIML Members cover 86% of the worlds population and 96% of its economy. The definition of legal metrology varies amongst jurisdictions, reflecting the extent to which metrology is bound into the jurisdictions own legal, the OIML, in their publication International Vocabulary of Terms in Legal Metrology defined legal metrology as. Concerns regulatory requirements of measurements and measuring instruments for the protection of health, public safety and these two statements are held together by the words regulatory, accuracy and reliability. The OIML has identified four main activities that fulfil the purposes of legal metrology, control/conformity assessment of regulated products and regulated activities. Supervision of regulated products and of regulated activities Providing the necessary infrastructure for correct measurements, under French law, its principal body, the International Conference is accorded diplomatic status. The convention that set up the OIML named eight purposes behind its establishment, to provide mutual recognition systems which reduce trade barriers and costs in a global market. To represent the interests of the legal metrology community within international organizations and forums concerned with metrology, standardization, testing, to promote and facilitate the exchange of knowledge and competencies within the legal metrology community worldwide. In co-operation with other bodies, to raise awareness of the contribution that a sound legal metrology infrastructure can make to a modern economy. To identify areas for the OIML to improve the effectiveness and efficiency of its work, the conference is attended by delegations from member countries and corresponding members of the organisation. The management of the OIML is vested in the International Committee, the committee, which consists of one member from each member state, meets annually under the chairmanship of the OIML president whose term of office lasts six years. Secretarial services, day-to-day running and financial management of the OIML are provided by the, the technical work of the OIML is carried out by technical committees, each committee having responsibility for a different aspect of legal metrology. In some cases the technical committee is broken up one or more subcommittees. The running of each subcommittee is the responsibility of national laboratories around the world. As of 4 February 2013 there were 18 technical committees and 45 subcommittees, the principal series include, Vocabularies that provide standardised terminology in the field of metrology. The OIML has produced two works, International Vocabulary of Terms in Legal Metrology which defines the terms used in legal metrology. The first edition of work was the joint effort of seven international organisations - BIPM, IEC, IFCC, ISO, IUPAC, IUPAP. Alphabetical list of defined in OIML Recommendations and Documents which defines the technical terms used in the various OIML recommendations
25.
Florida
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Florida /ˈflɒrᵻdə/ is a state located in the southeastern region of the United States. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia, to the east by the Atlantic Ocean, Florida is the 22nd-most extensive, the 3rd-most populous, and the 8th-most densely populated of the U. S. states. Jacksonville is the most populous municipality in the state and is the largest city by area in the contiguous United States, the Miami metropolitan area is Floridas most populous urban area. The city of Tallahassee is the state capital, much of the state is at or near sea level and is characterized by sedimentary soil. The climate varies from subtropical in the north to tropical in the south, the American alligator, American crocodile, Florida panther, and manatee can be found in the Everglades National Park. It was a location of the Seminole Wars against the Native Americans. Today, Florida is distinctive for its large Cuban expatriate community and high population growth, the states economy relies mainly on tourism, agriculture, and transportation, which developed in the late 19th century. Florida is also renowned for amusement parks, orange crops, the Kennedy Space Center, Florida has attracted many writers such as Marjorie Kinnan Rawlings, Ernest Hemingway and Tennessee Williams, and continues to attract celebrities and athletes. It is internationally known for golf, tennis, auto racing, by the 16th century, the earliest time for which there is a historical record, major Native American groups included the Apalachee, the Timucua, the Ais, the Tocobaga, the Calusa and the Tequesta. Florida was the first part of the continental United States to be visited and settled by Europeans, the earliest known European explorers came with the Spanish conquistador Juan Ponce de León. Ponce de León spotted and landed on the peninsula on April 2,1513 and he named the region La Florida. The story that he was searching for the Fountain of Youth is a myth, in May 1539, Conquistador Hernando de Soto skirted the coast of Florida, searching for a deep harbor to land. He described seeing a wall of red mangroves spread mile after mile, some reaching as high as 70 feet. Very soon, many smokes appeared along the whole coast, billowing against the sky, the Spanish introduced Christianity, cattle, horses, sheep, the Spanish language, and more to Florida. Both the Spanish and French established settlements in Florida, with varying degrees of success, in 1559, Don Tristán de Luna y Arellano established a settlement at present-day Pensacola, making it the first attempted settlement in Florida, but it was abandoned by 1561. Spain maintained tenuous control over the region by converting the tribes to Christianity. The area of Spanish Florida diminished with the establishment of English settlements to the north, the English attacked St. Augustine, burning the city and its cathedral to the ground several times. Florida attracted numerous Africans and African-Americans from adjacent British colonies who sought freedom from slavery, in 1738, Governor Manuel de Montiano established Fort Gracia Real de Santa Teresa de Mose near St
26.
Cafeteria
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Cafeterias are different from coffeehouses, despite being the Spanish translation of the English term. Instead of table service, there are food-serving counters/stalls, either in a line or allowing arbitrary walking paths, customers take the food that they desire as they walk along, placing it on a tray. Alternatively, the patron is given a number and the item is brought to his table. For some food items and drinks, such as sodas, water, or the like, customers collect an empty container, pay at the check-out, free unlimited second servings are often allowed under this system. For legal purposes, this system is rarely, if at all, customers are either charged a flat rate for admission or pay at the check-out for each item. Some self-service cafeterias charge by the weight of items on a patrons plate, in universities and colleges, some students pay for three meals a day by making a single large payment for the entire semester. As cafeterias require few employees, they are found within a larger institution. For example, schools, colleges and their halls, department stores, hospitals, museums, military bases, prisons. At one time, upscale cafeteria-style restaurants dominated the culture of the Southern United States, and to a lesser extent the Midwest. There were numerous prominent chains of them, Bickfords, Morrisons Cafeteria, Piccadilly Cafeteria, S&W Cafeteria, Apple House, Lubys, K&W, Britling, Wyatts Cafeteria, currently two Midwestern chains still exist, Sloppy Jos Lunchroom and Mannys, which are both located in Illinois. There were also a number of chains, usually located in. These institutions, with the exception of K&W, went into a decline in the 1960s with the rise of fast food and were finished off in the 1980s by the rise of casual dining. A few chains — particularly Lubys and Piccadilly Cafeterias — continue to some of the gap left by the decline of the older chains. Some of the smaller Midwestern chains, such as MCL Cafeterias centered on Indianapolis, are very much in business. Perhaps the first self-service restaurant in the US was the Exchange Buffet in New York City, opened September 4,1885, Food was purchased at a counter, and patrons ate standing up. This represents the predecessor of two formats, the cafeteria, described below, and the automat, during the 1893 Worlds Columbian Exposition in Chicago, entrepreneur John Kruger built an American version of the smörgåsbords he had seen while traveling in Sweden. Emphasizing the simplicity and light fare, he called it the Cafeteria - Spanish for coffee shop, the exposition attracted over 27 million visitors in six months, and because of Krugers operation that America first heard the term and experienced the self-service dining format. Meanwhile, in mid-scale America, the chain of Childs Restaurants quickly grew from about 10 locations in New York City in 1890 to hundreds across the US and Canada by 1920
27.
National Institute of Standards and Technology
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The National Institute of Standards and Technology is a measurement standards laboratory, and a non-regulatory agency of the United States Department of Commerce. Its mission is to promote innovation and industrial competitiveness, in 1821, John Quincy Adams had declared Weights and measures may be ranked among the necessities of life to every individual of human society. From 1830 until 1901, the role of overseeing weights and measures was carried out by the Office of Standard Weights and Measures, president Theodore Roosevelt appointed Samuel W. Stratton as the first director. The budget for the first year of operation was $40,000, a laboratory site was constructed in Washington, DC, and instruments were acquired from the national physical laboratories of Europe. In addition to weights and measures, the Bureau developed instruments for electrical units, in 1905 a meeting was called that would be the first National Conference on Weights and Measures. Quality standards were developed for products including some types of clothing, automobile brake systems and headlamps, antifreeze, during World War I, the Bureau worked on multiple problems related to war production, even operating its own facility to produce optical glass when European supplies were cut off. Between the wars, Harry Diamond of the Bureau developed a blind approach radio aircraft landing system, in 1948, financed by the Air Force, the Bureau began design and construction of SEAC, the Standards Eastern Automatic Computer. The computer went into operation in May 1950 using a combination of vacuum tubes, about the same time the Standards Western Automatic Computer, was built at the Los Angeles office of the NBS and used for research there. A mobile version, DYSEAC, was built for the Signal Corps in 1954, due to a changing mission, the National Bureau of Standards became the National Institute of Standards and Technology in 1988. Following 9/11, NIST conducted the investigation into the collapse of the World Trade Center buildings. NIST had a budget for fiscal year 2007 of about $843.3 million. NISTs 2009 budget was $992 million, and it also received $610 million as part of the American Recovery, NIST employs about 2,900 scientists, engineers, technicians, and support and administrative personnel. About 1,800 NIST associates complement the staff, in addition, NIST partners with 1,400 manufacturing specialists and staff at nearly 350 affiliated centers around the country. NIST publishes the Handbook 44 that provides the Specifications, tolerances, the Congress of 1866 made use of the metric system in commerce a legally protected activity through the passage of Metric Act of 1866. NIST is headquartered in Gaithersburg, Maryland, and operates a facility in Boulder, nISTs activities are organized into laboratory programs and extramural programs. Effective October 1,2010, NIST was realigned by reducing the number of NIST laboratory units from ten to six, nISTs Boulder laboratories are best known for NIST‑F1, which houses an atomic clock. NIST‑F1 serves as the source of the official time. NIST also operates a neutron science user facility, the NIST Center for Neutron Research, the NCNR provides scientists access to a variety of neutron scattering instruments, which they use in many research fields
28.
Mass
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In physics, mass is a property of a physical body. It is the measure of a resistance to acceleration when a net force is applied. It also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram, Mass is not the same as weight, even though mass is often determined by measuring the objects weight using a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity and this is because weight is a force, while mass is the property that determines the strength of this force. In Newtonian physics, mass can be generalized as the amount of matter in an object, however, at very high speeds, special relativity postulates that energy is an additional source of mass. Thus, any body having mass has an equivalent amount of energy. In addition, matter is a defined term in science. There are several distinct phenomena which can be used to measure mass, active gravitational mass measures the gravitational force exerted by an object. Passive gravitational mass measures the force exerted on an object in a known gravitational field. The mass of an object determines its acceleration in the presence of an applied force, according to Newtons second law of motion, if a body of fixed mass m is subjected to a single force F, its acceleration a is given by F/m. A bodys mass also determines the degree to which it generates or is affected by a gravitational field and this is sometimes referred to as gravitational mass. The standard International System of Units unit of mass is the kilogram, the kilogram is 1000 grams, first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the prototype kilogram. As of January 2013, there are proposals for redefining the kilogram yet again. In this context, the mass has units of eV/c2, the electronvolt and its multiples, such as the MeV, are commonly used in particle physics. The atomic mass unit is 1/12 of the mass of a carbon-12 atom, the atomic mass unit is convenient for expressing the masses of atoms and molecules. Outside the SI system, other units of mass include, the slug is an Imperial unit of mass, the pound is a unit of both mass and force, used mainly in the United States
29.
Buoyancy
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In science, buoyancy or upthrust, is an upward force exerted by a fluid that opposes the weight of an immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid, thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object and this pressure difference results in a net upwards force on the object. For this reason, an object whose density is greater than that of the fluid in which it is submerged tends to sink, If the object is either less dense than the liquid or is shaped appropriately, the force can keep the object afloat. This can occur only in a reference frame, which either has a gravitational field or is accelerating due to a force other than gravity defining a downward direction. In a situation of fluid statics, the net upward force is equal to the magnitude of the weight of fluid displaced by the body. The center of buoyancy of an object is the centroid of the volume of fluid. Archimedes principle is named after Archimedes of Syracuse, who first discovered this law in 212 B. C, more tersely, Buoyancy = weight of displaced fluid. The weight of the fluid is directly proportional to the volume of the displaced fluid. Thus, among completely submerged objects with equal masses, objects with greater volume have greater buoyancy and this is also known as upthrust. Suppose a rocks weight is measured as 10 newtons when suspended by a string in a vacuum with gravity acting upon it, suppose that when the rock is lowered into water, it displaces water of weight 3 newtons. The force it exerts on the string from which it hangs would be 10 newtons minus the 3 newtons of buoyancy force,10 −3 =7 newtons. Buoyancy reduces the apparent weight of objects that have sunk completely to the sea floor and it is generally easier to lift an object up through the water than it is to pull it out of the water. The density of the object relative to the density of the fluid can easily be calculated without measuring any volumes. Density of object density of fluid = weight weight − apparent immersed weight Example, If you drop wood into water, Example, A helium balloon in a moving car. During a period of increasing speed, the air mass inside the car moves in the direction opposite to the cars acceleration, the balloon is also pulled this way. However, because the balloon is buoyant relative to the air, it ends up being pushed out of the way, If the car slows down, the same balloon will begin to drift backward. For the same reason, as the car goes round a curve and this is the equation to calculate the pressure inside a fluid in equilibrium
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Friction
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Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction, Dry friction resists relative lateral motion of two surfaces in contact. Dry friction is subdivided into static friction between non-moving surfaces, and kinetic friction between moving surfaces, fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces, skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. Internal friction is the force resisting motion between the making up a solid material while it undergoes deformation. When surfaces in contact move relative to other, the friction between the two surfaces converts kinetic energy into thermal energy. This property can have consequences, as illustrated by the use of friction created by rubbing pieces of wood together to start a fire. Kinetic energy is converted to thermal energy whenever motion with friction occurs, another important consequence of many types of friction can be wear, which may lead to performance degradation and/or damage to components. Friction is a component of the science of tribology, Friction is not itself a fundamental force. Dry friction arises from a combination of adhesion, surface roughness, surface deformation. The complexity of interactions makes the calculation of friction from first principles impractical and necessitates the use of empirical methods for analysis. Friction is a non-conservative force - work done against friction is path dependent, in the presence of friction, some energy is always lost in the form of heat. Thus mechanical energy is not conserved, the Greeks, including Aristotle, Vitruvius, and Pliny the Elder, were interested in the cause and mitigation of friction. They were aware of differences between static and kinetic friction with Themistius stating in 350 A. D. that it is easier to further the motion of a moving body than to move a body at rest. The classic laws of sliding friction were discovered by Leonardo da Vinci in 1493, a pioneer in tribology and these laws were rediscovered by Guillaume Amontons in 1699. Amontons presented the nature of friction in terms of surface irregularities, the understanding of friction was further developed by Charles-Augustin de Coulomb. Coulomb further considered the influence of sliding velocity, temperature and humidity, the distinction between static and dynamic friction is made in Coulombs friction law, although this distinction was already drawn by Johann Andreas von Segner in 1758. Leslie was equally skeptical about the role of adhesion proposed by Desaguliers, in Leslies view, friction should be seen as a time-dependent process of flattening, pressing down asperities, which creates new obstacles in what were cavities before
31.
Thermal expansion
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Thermal expansion is the tendency of matter to change in shape, area, and volume in response to a change in temperature. Temperature is a function of the average molecular kinetic energy of a substance. When a substance is heated, the energy of its molecules increases. Thus, the molecules begin vibrating/moving more and usually maintain an average separation. Materials which contract with increasing temperature are unusual, this effect is limited in size, the degree of expansion divided by the change in temperature is called the materials coefficient of thermal expansion and generally varies with temperature. If an equation of state is available, it can be used to predict the values of the expansion at all the required temperatures and pressures. A number of contract on heating within certain temperature ranges. For example, the coefficient of expansion of water drops to zero as it is cooled to 3. Also, fairly pure silicon has a coefficient of thermal expansion for temperatures between about 18 and 120 Kelvin. Unlike gases or liquids, solid materials tend to keep their shape when undergoing thermal expansion, in general, liquids expand slightly more than solids. The thermal expansion of glasses is higher compared to that of crystals, at the glass transition temperature, rearrangements that occur in an amorphous material lead to characteristic discontinuities of coefficient of thermal expansion and specific heat. These discontinuities allow detection of the transition temperature where a supercooled liquid transforms to a glass. Absorption or desorption of water can change the size of common materials. Common plastics exposed to water can, in the long term, the coefficient of thermal expansion describes how the size of an object changes with a change in temperature. Specifically, it measures the change in size per degree change in temperature at a constant pressure. Several types of coefficients have been developed, volumetric, area, which is used depends on the particular application and which dimensions are considered important. For solids, one might only be concerned with the change along a length, the volumetric thermal expansion coefficient is the most basic thermal expansion coefficient, and the most relevant for fluids. In general, substances expand or contract when their temperature changes, substances that expand at the same rate in every direction are called isotropic
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Magnetic field
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A magnetic field is the magnetic effect of electric currents and magnetic materials. The magnetic field at any point is specified by both a direction and a magnitude, as such it is represented by a vector field. The term is used for two distinct but closely related fields denoted by the symbols B and H, where H is measured in units of amperes per meter in the SI, B is measured in teslas and newtons per meter per ampere in the SI. B is most commonly defined in terms of the Lorentz force it exerts on moving electric charges, Magnetic fields can be produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin. In quantum physics, the field is quantized and electromagnetic interactions result from the exchange of photons. Magnetic fields are used throughout modern technology, particularly in electrical engineering. The Earth produces its own field, which is important in navigation. Rotating magnetic fields are used in electric motors and generators. Magnetic forces give information about the carriers in a material through the Hall effect. The interaction of magnetic fields in electric devices such as transformers is studied in the discipline of magnetic circuits, noting that the resulting field lines crossed at two points he named those points poles in analogy to Earths poles. He also clearly articulated the principle that magnets always have both a north and south pole, no matter how finely one slices them, almost three centuries later, William Gilbert of Colchester replicated Petrus Peregrinus work and was the first to state explicitly that Earth is a magnet. Published in 1600, Gilberts work, De Magnete, helped to establish magnetism as a science, in 1750, John Michell stated that magnetic poles attract and repel in accordance with an inverse square law. Charles-Augustin de Coulomb experimentally verified this in 1785 and stated explicitly that the north and south poles cannot be separated, building on this force between poles, Siméon Denis Poisson created the first successful model of the magnetic field, which he presented in 1824. In this model, a magnetic H-field is produced by magnetic poles, three discoveries challenged this foundation of magnetism, though. First, in 1819, Hans Christian Ørsted discovered that an electric current generates a magnetic field encircling it, then in 1820, André-Marie Ampère showed that parallel wires having currents in the same direction attract one another. Finally, Jean-Baptiste Biot and Félix Savart discovered the Biot–Savart law in 1820, extending these experiments, Ampère published his own successful model of magnetism in 1825. This has the benefit of explaining why magnetic charge can not be isolated. Also in this work, Ampère introduced the term electrodynamics to describe the relationship between electricity and magnetism, in 1831, Michael Faraday discovered electromagnetic induction when he found that a changing magnetic field generates an encircling electric field
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Electrostatic field
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An electric field is a vector field that associates to each point in space the Coulomb force that would be experienced per unit of electric charge, by an infinitesimal test charge at that point. Electric fields are created by electric charges and can be induced by time-varying magnetic fields, the electric field combines with the magnetic field to form the electromagnetic field. The electric field, E, at a point is defined as the force, F. A particle of charge q would be subject to a force F = q E and its SI units are newtons per coulomb or, equivalently, volts per metre, which in terms of SI base units are kg⋅m⋅s−3⋅A−1. Electric fields are caused by electric charges or varying magnetic fields, in the special case of a steady state, the Maxwell-Faraday inductive effect disappears. The resulting two equations, taken together, are equivalent to Coulombs law, written as E =14 π ε0 ∫ d r ′ ρ r − r ′ | r − r ′ |3 for a charge density ρ. Notice that ε0, the permittivity of vacuum, must be substituted if charges are considered in non-empty media, the equations of electromagnetism are best described in a continuous description. A charge q located at r 0 can be described mathematically as a charge density ρ = q δ, conversely, a charge distribution can be approximated by many small point charges. Electric fields satisfy the principle, because Maxwells equations are linear. This principle is useful to calculate the field created by point charges. Q n are stationary in space at r 1, r 2, in that case, Coulombs law fully describes the field. If a system is static, such that magnetic fields are not time-varying, then by Faradays law, in this case, one can define an electric potential, that is, a function Φ such that E = − ∇ Φ. This is analogous to the gravitational potential, Coulombs law, which describes the interaction of electric charges, F = q = q E is similar to Newtons law of universal gravitation, F = m = m g. This suggests similarities between the electric field E and the gravitational field g, or their associated potentials, mass is sometimes called gravitational charge because of that similarity. Electrostatic and gravitational forces both are central, conservative and obey an inverse-square law, a uniform field is one in which the electric field is constant at every point. It can be approximated by placing two conducting plates parallel to other and maintaining a voltage between them, it is only an approximation because of boundary effects. Assuming infinite planes, the magnitude of the electric field E is, electrodynamic fields are E-fields which do change with time, for instance when charges are in motion. The electric field cannot be described independently of the field in that case
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Corrosion
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Corrosion is a natural process, which converts a refined metal to a more chemically-stable form, such as its oxide, hydroxide, or sulfide. It is the destruction of materials by chemical and/or electrochemical reaction with their environment. Corrosion engineering is the dedicated to controlling and stopping corrosion. In the most common use of the word, this means electrochemical oxidation of metal in reaction with an oxidant such as oxygen or sulfur, rusting, the formation of iron oxides, is a well-known example of electrochemical corrosion. This type of damage typically produces oxide or salt of the original metal, corrosion can also occur in materials other than metals, such as ceramics or polymers, although in this context, the term degradation is more common. Corrosion degrades the useful properties of materials and structures including strength, appearance and permeability to liquids, many structural alloys corrode merely from exposure to moisture in air, but the process can be strongly affected by exposure to certain substances. Corrosion can be concentrated locally to form a pit or crack, because corrosion is a diffusion-controlled process, it occurs on exposed surfaces. As a result, methods to reduce the activity of the surface, such as passivation and chromate conversion. However, some corrosion mechanisms are less visible and less predictable, in a galvanic couple, the more active metal corrodes at an accelerated rate and the more noble metal corrodes at a slower rate. When immersed separately, each metal corrodes at its own rate, what type of metal to use is readily determined by following the galvanic series. For example, zinc is used as a sacrificial anode for steel structures. Galvanic corrosion is of major interest to the industry and also anywhere water contacts pipes or metal structures. Factors such as size of anode, types of metal. The surface area ratio of the anode and cathode directly affects the corrosion rates of the materials, galvanic corrosion is often prevented by the use of sacrificial anodes. In any given environment, one metal will be more noble or more active than others. Two metals in electrical contact share the same electrons, so that the tug-of-war at each surface is analogous to competition for free electrons between the two materials. Using the electrolyte as a host for the flow of ions in the same direction, the resulting mass flow or electric current can be measured to establish a hierarchy of materials in the medium of interest. This hierarchy is called a series and is useful in predicting and understanding corrosion
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Condensation
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Condensation is the change of the physical state of matter from gas phase into liquid phase, and is the reverse of evaporation. The word most often refers to the water cycle and it can also be defined as the change in the state of water vapour to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within the atmosphere. When the transition happens from the phase into the solid phase directly. A few distinct reversibility scenarios emerge here with respect to the nature of the surface, absorption into the surface of a liquid —is reversible as evaporation. Adsorption onto solid surface at pressures and temperatures higher than the species triple point—also reversible as evaporation, adsorption onto solid surface at pressures and temperatures lower than the species triple point—is reversible as sublimation. Condensation commonly occurs when a vapor is cooled and/or compressed to its limit when the molecular density in the gas phase reaches its maximal threshold. Vapor cooling and compressing equipment that collects condensed liquids is called a condenser, psychrometry measures the rates of condensation through evaporation into the air moisture at various atmospheric pressures and temperatures. Water is the product of its vapor condensation—condensation is the process of such phase conversion, condensation is a crucial component of distillation, an important laboratory and industrial chemistry application. Because condensation is a naturally occurring phenomenon, it can often be used to water in large quantities for human use. Many structures are made solely for the purpose of collecting water from condensation, such as air wells and it is also a crucial process in forming particle tracks in a cloud chamber. In this case, ions produced by an incident particle act as centers for the condensation of the vapor producing the visible cloud trails. Furthermore, condensation is a step in many industrial processes, such as power generation, water desalination, thermal management, refrigeration. Numerous living beings use water made accessible by condensation, a few examples of these are the Australian Thorny Devil, the darkling beetles of the Namibian coast, and the Coast Redwoods of the West Coast of the United States. To alleviate these issues, the air humidity needs to be lowered. This can be done in a number of ways, for example opening windows, turning on extractor fans, using dehumidifiers, drying clothes outside and covering pots and pans whilst cooking. Air conditioning or ventilation systems can be installed that help remove moisture from the air, the amount of water vapour that can be stored in the air can be increased simply by increasing the temperature. However, this can be a double edged sword as most condensation in the home occurs when warm, as the air is cooled, it can no longer hold as much water vapour. This leads to deposition of water on the cool surface and this is very apparent when central heating is used in combination with single glazed windows in winter
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Evaporation
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Evaporation is a type of vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase that is not saturated with the evaporating substance. The other type of vaporization is boiling, which is characterized by bubbles of saturated vapor forming in the liquid phase, steam produced in a boiler is another example of evaporation occurring in a saturated vapor phase. Evaporation that occurs directly from the solid phase below the melting point, on average, a fraction of the molecules in a glass of water have enough heat energy to escape from the liquid. The water in the glass will be cooled by the evaporation until an equilibrium is reached where the air supplies the amount of heat removed by the evaporating water, in an enclosed environment the water would evaporate until the air is saturated. With sufficient temperature, the liquid would turn into vapor quickly, when the molecules collide, they transfer energy to each other in varying degrees, based on how they collide. Sometimes the transfer is so one-sided for a molecule near the surface that it ends up with energy to escape. Evaporation is an part of the water cycle. The sun drives evaporation of water from oceans, lakes, moisture in the soil, in hydrology, evaporation and transpiration are collectively termed evapotranspiration. Evaporation of water occurs when the surface of the liquid is exposed, allowing molecules to escape and form water vapor, when only a small proportion of the molecules meet these criteria, the rate of evaporation is low. Since the kinetic energy of a molecule is proportional to its temperature, as the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid decreases. This phenomenon is also called evaporative cooling and this is why evaporating sweat cools the human body. Evaporation also tends to proceed quickly with higher flow rates between the gaseous and liquid phase and in liquids with higher vapor pressure. For example, laundry on a line will dry more rapidly on a windy day than on a still day. Three key parts to evaporation are heat, atmospheric pressure, on a molecular level, there is no strict boundary between the liquid state and the vapor state. Instead, there is a Knudsen layer, where the phase is undetermined, because this layer is only a few molecules thick, at a macroscopic scale a clear phase transition interface cannot be seen. It is just that the process is slower and thus significantly less visible. If evaporation takes place in an area, the escaping molecules accumulate as a vapor above the liquid. Many of the return to the liquid, with returning molecules becoming more frequent as the density
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Convection
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Convection is the movement of groups of molecules within fluids such as liquids or gases, and within rheids. Convection takes place through advection, diffusion or both, convection cannot take place in solids because neither bulk current flows nor significant diffusion can take place in solids. Diffusion of heat can take place in solids, but that is called heat conduction, convective heat transfer is one of the major types of heat transfer, and convection is also a major mode of mass transfer in fluids. In the context of heat and mass transfer, the convection is used to refer to the sum of advective and diffusive transfer. In common use the term convection may refer loosely to heat transfer by convection, as opposed to mass transfer by convection, sometimes convection is even used to refer specifically to free heat convection as opposed to forced heat convection. However, in mechanics the correct use of the word is the general sense, convection can be qualified in terms of being natural, forced, gravitational, granular, or thermomagnetic. It may also be said to be due to combustion, capillary action, or Marangoni, heat transfer by natural convection plays a role in the structure of Earths atmosphere, its oceans, and its mantle. Discrete convective cells in the atmosphere can be seen as clouds, natural convection also plays a role in stellar physics. The word convection may have different but related usages in different scientific or engineering contexts or applications. The broader sense is in fluid mechanics, where convection refers to the motion of fluid regardless of cause, however, in thermodynamics convection often refers specifically to heat transfer by convection. Additionally, convection includes fluid movement both by bulk motion and by the motion of individual particles, however, in some cases, convection is taken to mean only advective phenomena. Convection occurs on a scale in atmospheres, oceans, planetary mantles. Fluid movement during convection may be slow, or it may be obvious and rapid. On astronomical scales, convection of gas and dust is thought to occur in the disks of black holes. Convective heat transfer is a mechanism of heat transfer occurring because of bulk motion of fluids, heat is the entity of interest being advected, and diffused. Heat is transferred by convection in numerous examples of naturally occurring fluid flow, such as, wind, oceanic currents, convection is also used in engineering practices of homes, industrial processes, cooling of equipment, etc. The rate of heat transfer may be improved by the use of a heat sink. For instance, a typical computer CPU will have a fan to ensure its operating temperature is kept within tolerable limits
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Book of the Dead
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The Book of the Dead is an ancient Egyptian funerary text, used from the beginning of the New Kingdom to around 50 BCE. The original Egyptian name for the text, transliterated rw nw prt m hrw is translated as Book of Coming Forth by Day, another translation would be Book of Emerging Forth into the Light. The Book of the Dead was part of a tradition of texts which includes the earlier Pyramid Texts and Coffin Texts. Some of the spells included were drawn from older works. Other spells were composed later in Egyptian history, dating to the Third Intermediate Period, a number of the spells which made up the Book continued to be inscribed on tomb walls and sarcophagi, as had always been the spells from which they originated. The Book of the Dead was placed in the coffin or burial chamber of the deceased, there was no single or canonical Book of the Dead. The surviving papyri contain a selection of religious and magical texts. Some people seem to have commissioned their own copies of the Book of the Dead, the Book of the Dead developed from a tradition of funerary manuscripts dating back to the Egyptian Old Kingdom. The first funerary texts were the Pyramid Texts, first used in the Pyramid of King Unas of the 5th dynasty and these texts were written on the walls of the burial chambers within pyramids, and were exclusively for the use of the Pharaoh. Towards the end of the Old Kingdom, the Pyramid Texts ceased to be a royal privilege. In the Middle Kingdom, a new funerary text emerged, the Coffin Texts, the Coffin Texts used a newer version of the language, new spells, and included illustrations for the first time. The Coffin Texts were most commonly written on the surfaces of coffins. The Book of the Dead first developed in Thebes towards the beginning of the Second Intermediate Period, by the 17th dynasty, the Book of the Dead had become widespread not only for members of the royal family, but courtiers and other officials as well. At this stage, the spells were typically inscribed on linen shrouds wrapped around the dead, the New Kingdom saw the Book of the Dead develop and spread further. The famous Spell 125, the Weighing of the Heart, is first known from the reign of Hatshepsut and Thutmose III, from this period onward the Book of the Dead was typically written on a papyrus scroll, and the text illustrated with vignettes. During the 19th dynasty in particular, the vignettes tended to be lavish, in the Third Intermediate Period, the Book of the Dead started to appear in hieratic script, as well as in the traditional hieroglyphics. The hieratic scrolls were a version, lacking illustration apart from a single vignette at the beginning. At the same time, many burials used additional funerary texts, during the 25th and 26th dynasties, the Book of the Dead was updated, revised and standardised
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Maat
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Maat or Maat was the ancient Egyptian concept of truth, balance, order, harmony, law, morality, and justice. Maat was also personified as a goddess regulating the stars, seasons, cuneiform texts indicate that the word mˤ3t was pronounced /múʕʔa/ during the New Kingdom period, having lost the feminine ending t. Sound shifts from u to e later produced the cognate Coptic word ⲙⲉⲉ/ⲙⲉ truth, later, as a goddess in other traditions of the Egyptian pantheon, where most goddesses were paired with a male aspect, her masculine counterpart was Thoth, as their attributes are similar. In other accounts, Thoth was paired off with Seshat, goddess of writing and measure and her feather was the measure that determined whether the souls of the departed would reach the paradise of afterlife successfully. Pharaohs are often depicted with the emblems of Maat to emphasise their role in upholding the laws of the Creator, Maat represents the ethical and moral principle that every Egyptian citizen was expected to follow throughout their daily lives. They were expected to act with honor and truth in manners that involve family, the community, the nation, the environment, Maat as a principle was formed to meet the complex needs of the emergent Egyptian state that embraced diverse peoples with conflicting interests. The development of such rules sought to avert chaos and it became the basis of Egyptian law, from an early period the King would describe himself as the Lord of Maat who decreed with his mouth the Maat he conceived in his heart. The ancient Egyptians had a conviction of an underlying holiness. Cosmic harmony was achieved by public and ritual life. Any disturbance in cosmic harmony could have consequences for the individual as well as the state, an impious King could bring about famine or blasphemy blindness to an individual. In opposition to the order expressed in the concept of Maat is the concept of Isfet, chaos, lies. In one Middle Kingdom text the Creator declares I made every man like his fellow, a passage in the Instruction of Ptahhotep presents Maat as follows, Maat is good and its worth is lasting. It has not been disturbed since the day of its creator and it lies as a path in front even of him who knows nothing. Wrongdoing has never yet brought its venture to port and it is true that evil may gain wealth but the strength of truth is that it lasts, a man can say, It was the property of my father. There is little surviving literature that describes the practice of ancient Egyptian law, Maat was the spirit in which justice was applied rather than the detailed legalistic exposition of rules. Maat represented the normal and basic values that formed the backdrop for the application of justice that had to be carried out in the spirit of truth and fairness. From the 5th dynasty onwards the Vizier responsible for justice was called the Priest of Maat, later scholars and philosophers also would embody concepts from the wisdom literature, or Sebayt. These spiritual texts dealt with social or professional situations and how each was best to be resolved or addressed in the spirit of Maat
40.
Chu (state)
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Chu was a hegemonic, Zhou dynasty era state. From King Wu of Chu in the early 8th century BCE, with its continued expansion Chu became a great Warring States period power. Also known as Jing, Jingchu and Shu, Chu included most of the provinces of Hubei and Hunan, along with parts of Chongqing, Guizhou, Henan, Anhui, Jiangxi, Jiangsu, Zhejiang. For more than 400 years, the Chu capital Danyang was located at the junction of the Dan and Xi Rivers near present-day Xichuan County, Henan, but later moved to Ying. The ruling house of Chu originally bore the clan name Nai and lineage name Yan, according to legends recounted in Sima Qians Records of the Grand Historian, the royal family of Chu descended from the Yellow Emperor and his grandson and successor Zhuanxu. Zhuanxus great-grandson Wuhui was put in charge of fire by Emperor Ku, wuhuis son Luzhong had six sons, all born by Caesarian section. The youngest, Jilian, adopted the ancestral surname Mi, jilian’s descendant Yuxiong was the teacher of King Wen of Zhou. After the Zhou overthrew the Shang dynasty, King Cheng awarded Yuxiongs great-grandson Xiong Yi with the fiefdom of Chu, Xiong Yi built the first capital of Chu at Danyang. In 977 BCE, during his campaign against Chu, King Zhao of Zhous boat sank, after this death, Zhou ceased to expand to the south, allowing the southern tribes and Chu to cement their own autonomy much earlier than the states to the north. The Chu viscount Xiong Qu overthrew E in 863 BCE but subsequently made its capital Ezhou one of his capitals, in either 703 or 706, the ruler Xiong Tong proclaimed himself king, establishing Chus full independence from the Zhou dynasty. In its early years, Chu was a successful expansionist and militaristic state that developed a reputation for coercing and absorbing its allies, Chu grew from a small state into a large kingdom. King Zhuang was even considered one of the five Hegemons of the era, after a number of battles with neighboring states, sometime between 695 and 689 BCE, the Chu capital moved southeast from Danyang to Ying. Chu first consolidated its power by absorbing lesser states in its original area, the threat from Chu resulted in multiple northern alliances under the leadership of Jin. These alliances kept Chu in check, with the first major victory won at the Chengpu in 632 BCE, at the beginning of the sixth century BCE, Jin strengthened the state of Wu near the Yangtze delta to act as a counterweight against Chu. Wu defeated Qi and then invaded Chu in 506 BCE, following the Battle of Boju, it occupied Chus capital at Ying, forcing King Zhao to flee to his allies in Yun and Sui. King Zhao eventually returned to Ying but, after another attack from Wu in 504 BCE, Chu began to strengthen Yue in modern Zhejiang to serve as allies against Wu. Yue was initially subjugated by King Fuchai of Wu until he released their king Goujian, freed from its difficulties with Wu, Chu annexed Chen in 479 BCE and overran Cai to the north in 447 BCE. This policy of expansion continued until the last generation before the fall to Qin, however, by the end of the 5th century BCE, the Chu government had become very corrupt and inefficient, with much of the states treasury used primarily to pay for the royal entourage
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Warring States period
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The Warring States Period derives its name from the Record of the Warring States, a work compiled early in the Han dynasty. The political geography of the era was dominated by the Seven Warring States, namely, Qin, The State of Qin was in the far west, with its core in the Wei River Valley and Guanzhong. This geographical position offered protection from the states of the Central Plains, the Three Jins, Northeast of Qin, on the Shanxi plateau, were the three successor states of Jin. These were, Han, south, along the Yellow River, Zhao, the northernmost of the three. Qi, located in the east of China, centred on the Shandong Peninsula, described as east of Mount Tai, Chu, located in the south of China, with its core territory around the valleys of the Han River and, later, the Yangtze River. Yan, located in the northeast, centred on modern-day Beijing, late in the period Yan pushed northeast and began to occupy the Liaodong Peninsula Besides these seven major states, some minor states also survived into the period. Yue, On the southeast coast near Shanghai was the State of Yue, Sichuan, In the far southwest were the States of Ba and Shu. These were non-Zhou states that were conquered by Qin late in the period, in the Central Plains comprising much of modern-day Henan Province, many smaller city states survived as satellites of the larger states, though they were eventually to be absorbed as well. Zhongshan, Between the states of Zhao and Yan was the state of Zhongshan, the Spring and Autumn period was initiated by the eastward flight of the Zhou court. There is no one single incident or starting point for the Warring States era, some proposed starting points are as follows,481 BC, Proposed by Song-era historian Lü Zuqian, since it is the end of the Spring and Autumn Annals. 476–475 BC, The author, Sima Qian, of Records of the Grand Historian who chose the year of King Yuan of Zhou. 403 BC, The year when Han, Zhao and Wei were officially recognised as states by the Zhou court, author Sima Guang of Zizhi Tongjian tells us that the symbol of eroded Zhou authority should be taken as the start of the Warring States era. The Spring and Autumn period led to a few states gaining power at the expense of many others, during the Warring States period, many rulers claimed the Mandate of Heaven to justify their conquest of other states and spread their influence. Other major states also existed, such as Wu and Yue in the southeast, the last decades of the Spring and Autumn era were marked by increased stability, as the result of peace negotiations between Jin and Chu which established their respective spheres of influence. This situation ended with the partition of Jin, whereby the state was divided between the houses of Han, Zhao and Wei, and thus enabled the creation of the seven major warring states. This allowed other clans to gain fiefs and military authority, and decades of struggle led to the establishment of four major families. The Battle of Jinyang saw the allied Han, Zhao and Wei destroy the Zhi family, with this, they became the de facto rulers of most of Jins territory, though this situation would not be officially recognised until half a century later. The Jin division created a vacuum that enabled during the first 50 years expansion of Chu and Yue northward
