1.
System of measurement
–
A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce, systems of measurement in modern use include the metric system, the imperial system, and United States customary units. The French Revolution gave rise to the system, and this has spread around the world. In most systems, length, mass, and time are base quantities, later science developments showed that either electric charge or electric current could be added to extend the set of base quantities by which many other metrological units could be easily defined. Other quantities, such as power and speed, are derived from the set, for example. Such arrangements were satisfactory in their own contexts, the preference for a more universal and consistent system only gradually spread with the growth of science. Changing a measurement system has substantial financial and cultural costs which must be offset against the advantages to be obtained using a more rational system. However pressure built up, including scientists and engineers for conversion to a more rational. The unifying characteristic is that there was some definition based on some standard, eventually cubits and strides gave way to customary units to met the needs of merchants and scientists. In the metric system and other recent systems, a basic unit is used for each base quantity. Often secondary units are derived from the units by multiplying by powers of ten. Thus the basic unit of length is the metre, a distance of 1.234 m is 1,234 millimetres. Metrication is complete or nearly complete in almost all countries, US customary units are heavily used in the United States and to some degree in Liberia. Traditional Burmese units of measurement are used in Burma, U. S. units are used in limited contexts in Canada due to the large volume of trade, there is also considerable use of Imperial weights and measures, despite de jure Canadian conversion to metric. In the United States, metric units are used almost universally in science, widely in the military, and partially in industry, but customary units predominate in household use. At retail stores, the liter is a used unit for volume, especially on bottles of beverages. Some other standard non-SI units are still in use, such as nautical miles and knots in aviation. Metric systems of units have evolved since the adoption of the first well-defined system in France in 1795, during this evolution the use of these systems has spread throughout the world, first to non-English-speaking countries, and then to English speaking countries
2.
International System of Units
–
The International System of Units is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, the system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system was published in 1960 as the result of an initiative began in 1948. It is based on the system of units rather than any variant of the centimetre-gram-second system. The motivation for the development of the SI was the diversity of units that had sprung up within the CGS systems, the International System of Units has been adopted by most developed countries, however, the adoption has not been universal in all English-speaking countries. The metric system was first implemented during the French Revolution with just the metre and kilogram as standards of length, in the 1830s Carl Friedrich Gauss laid the foundations for a coherent system based on length, mass, and time. In the 1860s a group working under the auspices of the British Association for the Advancement of Science formulated the requirement for a coherent system of units with base units and derived units. Meanwhile, in 1875, the Treaty of the Metre passed responsibility for verification of the kilogram, in 1921, the Treaty was extended to include all physical quantities including electrical units originally defined in 1893. The units associated with these quantities were the metre, kilogram, second, ampere, kelvin, in 1971, a seventh base quantity, amount of substance represented by the mole, was added to the definition of SI. On 11 July 1792, the proposed the names metre, are, litre and grave for the units of length, area, capacity. The committee also proposed that multiples and submultiples of these units were to be denoted by decimal-based prefixes such as centi for a hundredth, on 10 December 1799, the law by which the metric system was to be definitively adopted in France was passed. Prior to this, the strength of the magnetic field had only been described in relative terms. The technique used by Gauss was to equate the torque induced on a magnet of known mass by the earth’s magnetic field with the torque induced on an equivalent system under gravity. The resultant calculations enabled him to assign dimensions based on mass, length, a French-inspired initiative for international cooperation in metrology led to the signing in 1875 of the Metre Convention. Initially the convention only covered standards for the metre and the kilogram, one of each was selected at random to become the International prototype metre and International prototype kilogram that replaced the mètre des Archives and kilogramme des Archives respectively. Each member state was entitled to one of each of the prototypes to serve as the national prototype for that country. Initially its prime purpose was a periodic recalibration of national prototype metres. The official language of the Metre Convention is French and the version of all official documents published by or on behalf of the CGPM is the French-language version
3.
SI base unit
–
The International System of Units defines seven units of measure as a basic set from which all other SI units can be derived. The SI base units form a set of mutually independent dimensions as required by dimensional analysis commonly employed in science, thus, the kelvin, named after Lord Kelvin, has the symbol K and the ampere, named after André-Marie Ampère, has the symbol A. Many other units, such as the litre, are not part of the SI. The definitions of the units have been modified several times since the Metre Convention in 1875. Since the redefinition of the metre in 1960, the kilogram is the unit that is directly defined in terms of a physical artifact. However, the mole, the ampere, and the candela are linked through their definitions to the mass of the platinum–iridium cylinder stored in a vault near Paris. It has long been an objective in metrology to define the kilogram in terms of a fundamental constant, two possibilities have attracted particular attention, the Planck constant and the Avogadro constant. The 23rd CGPM decided to postpone any formal change until the next General Conference in 2011
4.
Megagram (geometry)
–
A megagon or 1000000-gon is a polygon with 1 million sides. Even if drawn at the size of the Earth, a regular megagon would be difficult to distinguish from a circle. A regular megagon has an angle of 179. 99964°. The area of a regular megagon with sides of length a is given by A =250000 a 2 cot π1000000, the perimeter of a regular megagon inscribed in the unit circle is,2000000 sin π1000000, which is very close to 2π. In fact, for a circle the size of the Earths equator, with a circumference of 40,075 kilometres, the difference between the perimeter of the inscribed megagon and the circumference of this circle comes to less than 1/16 millimeters. Because 1000000 =26 ×56, the number of sides is not a product of distinct Fermat primes, thus the regular megagon is not a constructible polygon. Indeed, it is not even constructible with the use of neusis or an angle trisector, as the number of sides is neither a product of distinct Pierpont primes, nor a product of powers of two and three. Like René Descartes example of the chiliagon, the polygon has been used as an illustration of a well-defined concept that cannot be visualised. The megagon is also used as an illustration of the convergence of regular polygons to a circle, the regular megagon has Dih1000000 dihedral symmetry, order 2000000, represented by 1000000 lines of reflection. Dih100 has 48 dihedral subgroups, and and it also has 49 more cyclic symmetries as subgroups, and, with Zn representing π/n radian rotational symmetry. John Conway labels these symmetries with a letter and order of the symmetry follows the letter. R2000000 represents full symmetry and a1 labels no symmetry and he gives d with mirror lines through vertices, p with mirror lines through edges, i with mirror lines through both vertices and edges, and g for rotational symmetry. These lower symmetries allows degrees of freedom in defining irregular megagons, only the g1000000 subgroup has no degrees of freedom but can seen as directed edges. A megagram is a star polygon. There are 199,999 regular forms given by Schläfli symbols of the form, there are also 300,000 regular star figures in the remaining cases
5.
Metric system
–
The metric system is an internationally agreed decimal system of measurement. Many sources also cite Liberia and Myanmar as the other countries not to have done so. Although the originators intended to devise a system that was accessible to all. Control of the units of measure was maintained by the French government until 1875, when it was passed to an intergovernmental organisation. From its beginning, the features of the metric system were the standard set of interrelated base units. These base units are used to larger and smaller units that could replace a huge number of other units of measure in existence. Although the system was first developed for use, the development of coherent units of measure made it particularly suitable for science. Although the metric system has changed and developed since its inception, designed for transnational use, it consisted of a basic set of units of measurement, now known as base units. At the outbreak of the French Revolution in 1789, most countries, the metric system was designed to be universal—in the words of the French philosopher Marquis de Condorcet it was to be for all people for all time. However, these overtures failed and the custody of the metric system remained in the hands of the French government until 1875. In languages where the distinction is made, unit names are common nouns, the concept of using consistent classical names for the prefixes was first proposed in a report by the Commission on Weights and Measures in May 1793. The prefix kilo, for example, is used to multiply the unit by 1000, thus the kilogram and kilometre are a thousand grams and metres respectively, and a milligram and millimetre are one thousandth of a gram and metre respectively. These relations can be written symbolically as,1 mg =0, however,1935 extensions to the prefix system did not follow this convention, the prefixes nano- and micro-, for example have Greek roots. During the 19th century the prefix myria-, derived from the Greek word μύριοι, was used as a multiplier for 10000, prefixes are not usually used to indicate multiples of a second greater than 1, the non-SI units of minute, hour and day are used instead. On the other hand, prefixes are used for multiples of the unit of volume. The base units used in the system must be realisable. Each of the units in SI is accompanied by a mise en pratique published by the BIPM that describes in detail at least one way in which the base unit can be measured. In practice, such realisation is done under the auspices of a mutual acceptance arrangement, in the original version of the metric system the base units could be derived from a specified length and the weight of a specified volume of pure water
6.
Mass
–
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
7.
Kilogram
–
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
8.
Pound (mass)
–
The pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement. The international standard symbol for the pound is lb. The unit is descended from the Roman libra, the English word pound is cognate with, among others, German Pfund, Dutch pond, and Swedish pund. All ultimately derive from a borrowing into Proto-Germanic of the Latin expression lībra pondō, usage of the unqualified term pound reflects the historical conflation of mass and weight. This accounts for the modern distinguishing terms pound-mass and pound-force, the United States and countries of the Commonwealth of Nations agreed upon common definitions for the pound and the yard. Since 1 July 1959, the avoirdupois pound has been defined as exactly 0.45359237 kg. In the United Kingdom, the use of the pound was implemented in the Weights and Measures Act 1963.9144 metre exactly. An avoirdupois pound is equal to 16 avoirdupois ounces and to exactly 7,000 grains, the conversion factor between the kilogram and the international pound was therefore chosen to be divisible by 7, and an grain is thus equal to exactly 64.79891 milligrams. The US has not adopted the system despite many efforts to do so. Historically, in different parts of the world, at different points in time, and for different applications, the libra is an ancient Roman unit of mass that was equivalent to approximately 328.9 grams. It was divided into 12 unciae, or ounces, the libra is the origin of the abbreviation for pound, lb. A number of different definitions of the pound have historically used in Britain. Amongst these were the avoirdupois pound and the tower, merchants. Historically, the sterling was a tower pound of silver. In 1528, the standard was changed to the Troy pound, the avoirdupois pound, also known as the wool pound, first came into general use c. It was initially equal to 6992 troy grains, the pound avoirdupois was divided into 16 ounces. During the reign of Queen Elizabeth, the pound was redefined as 7,000 troy grains. Since then, the grain has often been a part of the avoirdupois system
9.
National Institute of Standards and Technology
–
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
10.
Tesla (unit)
–
The tesla is a unit of measurement of the strength of a magnetic field. It is a unit of the International System of Units. One tesla is equal to one weber per square metre, the unit was announced during the General Conference on Weights and Measures in 1960 and is named in honour of Nikola Tesla, upon the proposal of the Slovenian electrical engineer France Avčin. The strongest fields encountered from permanent magnets are from Halbach spheres, the strongest field trapped in a laboratory superconductor as of June 2014 is 21 T. This may be appreciated by looking at the units for each, the unit of electric field in the MKS system of units is newtons per coulomb, N/C, while the magnetic field can be written as N/. The dividing factor between the two types of field is metres per second, which is velocity, in ferromagnets, the movement creating the magnetic field is the electron spin. In a current-carrying wire the movement is due to moving through the wire. One tesla is equivalent to,10,000 G, used in the CGS system, thus,10 kG =1 T, and 1 G = 10−4 T.1,000,000,000 γ, used in geophysics. Thus,1 γ =1 nT.42.6 MHz of the 1H nucleus frequency, thus, the magnetic field associated with NMR at 1 GHz is 23.5 T. One tesla is equal to 1 V·s/m2 and this can be shown by starting with the speed of light in vacuum, c = −1/2, and inserting the SI values and units for c, the vacuum permittivity ε0, and the vacuum permeability μ0. Cancellation of numbers and units then produces this relation, for those concerned with low-frequency electromagnetic radiation in the home, the following conversions are needed most,1000 nT =1 µT =10 mG,1,000,000 µT =1 T. For the relation to the units of the field, see the article on permeability
11.
TNT equivalent
–
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The ton of TNT is a unit of energy defined by convention to be 4.184 gigajoules. The convention intends to compare the destructiveness of an event with that of conventional explosives, the kiloton is a unit of energy equal to 4.184 terajoules. The megaton is a unit of equal to 4.184 petajoules. The kiloton and megaton of TNT have traditionally used to describe the energy output. The TNT equivalent appears in various nuclear weapon control treaties, and has used to characterize the energy released in such other highly destructive events as an asteroid impact. A gram of TNT releases 2673–6702 J upon explosion, the energy liberated by one gram of TNT was arbitrarily defined as a matter of convention to be 4184 J, which is exactly one kilocalorie. The measured, pure heat output of a gram of TNT is only 2724 J, alternative TNT equivalency can be calculated as a function of when in the detonation the value is measured and which property is being compared. A kiloton of TNT can be visualized as a cube of TNT8.46 metres on a side, the RE factor is the relative mass of TNT to which an explosive is equivalent, the greater the RE, the more powerful the explosive. This enables engineers to determine the proper masses of different explosives when applying blasting formulas developed specifically for TNT. For example, if a timber-cutting formula calls for a charge of 1 kg of TNT, then based on octanitrocubanes RE factor of 2.38, using PETN, engineers would need 1. 0/1.66 kg to obtain the same effects as 1 kg of TNT. With ANFO or ammonium nitrate, they would require 1. 0/0.74 kg or 1. 0/0.42 kg, *, TBX or EBX, in a small, confined space, may have over twice the power of destruction. The total power of aluminized mixtures strictly depends on the condition of explosions, guide for the Use of the International System of Units. National Institute of Standards and Technology, nuclear Weapons FAQ Part 1.3 Rhodes, Richard. The Making of the Atomic Bomb, cooper, Paul W. Explosives Engineering, New York, Wiley-VCH, ISBN 0-471-18636-8 HQ Department of the Army, Field Manual 5-25, Explosives and Demolitions, Washington, D. C. Pentagon Publishing, pp. 83–84, ISBN 0-9759009-5-1 Explosives - Compositions, Alexandria, VA, thermobaric Explosives, Advanced Energetic Materials,2004. THE NATIONAL ACADEMIES PRESS, nap. edu, retrieved September 2004
12.
Petajoules
–
The joule, symbol J, is a derived unit of energy in the International System of Units. It is equal to the transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. It is also the energy dissipated as heat when a current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule, one joule can also be defined as, The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb volt. This relationship can be used to define the volt, the work required to produce one watt of power for one second, or one watt second. This relationship can be used to define the watt and this SI unit is named after James Prescott Joule. As with every International System of Units unit named for a person, note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. The CGPM has given the unit of energy the name Joule, the use of newton metres for torque and joules for energy is helpful to avoid misunderstandings and miscommunications. The distinction may be also in the fact that energy is a scalar – the dot product of a vector force. By contrast, torque is a vector – the cross product of a distance vector, torque and energy are related to one another by the equation E = τ θ, where E is energy, τ is torque, and θ is the angle swept. Since radians are dimensionless, it follows that torque and energy have the same dimensions, one joule in everyday life represents approximately, The energy required to lift a medium-size tomato 1 m vertically from the surface of the Earth. The energy released when that same tomato falls back down to the ground, the energy required to accelerate a 1 kg mass at 1 m·s−2 through a 1 m distance in space. The heat required to raise the temperature of 1 g of water by 0.24 °C, the typical energy released as heat by a person at rest every 1/60 s. The kinetic energy of a 50 kg human moving very slowly, the kinetic energy of a 56 g tennis ball moving at 6 m/s. The kinetic energy of an object with mass 1 kg moving at √2 ≈1.4 m/s, the amount of electricity required to light a 1 W LED for 1 s. Since the joule is also a watt-second and the unit for electricity sales to homes is the kW·h. For additional examples, see, Orders of magnitude The zeptojoule is equal to one sextillionth of one joule,160 zeptojoules is equivalent to one electronvolt. The nanojoule is equal to one billionth of one joule, one nanojoule is about 1/160 of the kinetic energy of a flying mosquito
13.
Metrication in the United Kingdom
–
Metrication in the United Kingdom is the process of introducing the metric system of measurement in place of imperial units in the United Kingdom. Metrication in the United Kingdom remains equivocal and varies by context, Imperial units are also often used informally to describe body measurements and vehicle fuel economy. In schools, the use of units is the norm, however. Adopting the metric system was discussed in Parliament as early as 1818 and some industries and even some government agencies had metricated, however, a formal government policy to support metrication was not agreed until 1965. This policy, initiated in response to requests from industry, was to support voluntary metrication, in 1969 the government created the Metrication Board as a quango to promote and coordinate metrication. In 1980 government policy shifted again to prefer voluntary metrication, by the time the Metrication Board was wound up, all the economic sectors that fell within its remit except road signage and parts of the retail trade sector had metricated. By 1980 most pre-packaged goods were sold using the prescribed units, mandatory use of prescribed units for retail sales took effect in 1995 for packaged goods and in 2000 for goods sold loose by weight. The use of supplementary indications or alternative units was originally to have been permitted for only a limited period, however, the British Government has often seemed lukewarm in its support of the metric system. When James VI of Scotland inherited the English throne in 1603, in 1707, under the Act of Union, the Parliaments of England and Scotland were merged and the English units of measurement became the standard for the whole new Kingdom of Great Britain. However, the effect of this was that both systems were used in Scotland, and the Scottish measures remained in common use until the Weights. This period marked the Age of Enlightenment, when people started using the power of reason to reform society, gunters chain was one chain in length and consisted of 100 links, making each link 0.001 furlongs. The decimal nature of these units and of the device made it easy to calculate the area of a rectangle of land in acres and decimal fractions of an acre. In 1670, John Wilkins, the first president of the Royal Society, published his proposal for a system of measure, in his work An Essay towards a Real Character. He recycled the existing names of units of measure, so there were 10 lines in an inch,10 inches in a foot. A century later, his concept of defining unit mass in terms of a cube of water with edges of length was one of the fundamental concepts of the metric system. Having difficulties in communicating with German scientists, the Scottish inventor James Watt, in 1783, the French continued alone and created the foundations of what is now called the Système International dUnités and is the measurement system for most of the world. In 1799, the French created, and started to use, a new system with the metre, as use of this new system, originally called the Decimal System, spread through Europe, there were some calls in the United Kingdom for decimalisation. The issue of decimalisation of measurement was intertwined in the United Kingdom with decimalisation of currency, the idea was first discussed by a Royal Commission that reported in 1818, and again in Parliament by Sir John Wrottesley in 1824
14.
Weights and Measures Acts (UK)
–
Weights and measures acts are acts of the British Parliament determining the regulation of weights and measures. It also refers to similar royal and parliamentary acts of the Kingdoms of England and Scotland, the earliest of these were originally untitled but were given descriptive glosses or titles based upon the monarch under whose reign they were promulgated. Several omnibus modern acts are entitled the Weights and Measures Act and are distinguished by the year of their enactment, There have been many laws concerned with weights and measures in the United Kingdom or parts of it over the last 1000 or so years. Modern legislation may, in addition to requirements, set out circumstances under which the incumbent minister may amend the legislation by means of statutory instruments. Prior to the Weights and Measures Act of 1985, weights, the 1985 act, however, had a broader scope, encompassing all aspects covered by the European Economic Community European Commission directive 80/181/EEC. As of 25 April 2012, the current primary legislation in the United Kingdom is the 1985 Act, statutory instruments made under the authority of the Act do not amend the Act per se, but regulate particular areas covered by the Act. The Act is currently enforced by the 200 Trading Standards Offices managed by local authorities around the country, the Weights and Measures Act of 1897 made the provision that metric units could be used in addition to the traditional imperial units for purposes of trade. In practice, the choice of units was restricted by price marking orders which listed packaging sizes. For example, as of April 2012, wine for consumption on premises may only be sold in 125,175, prior to 1973, when the United Kingdom joined the EEC, such specifications were almost all in imperial units. To comply with this directive, the Weights and Measures Act of 1986 extended the scope of Trading Standards responsibilities from just matters related to trade to all aspects of the directive. For example, it was the Trading Standards Office that criticised the use of sub-standard weighing machines in NHS hospitals, the initial intention was to prohibit dual labelling after the end of 1989, with metric units only being allowed after that date. This deadline was extended, first to the end of 1999. Finally, in 2007, the European Union and the EC, confirmed that the UK would be permitted to continue indefinitely to use imperial units such as pints, miles, pounds and ounces as at present. The Gloucestershire County Council Trading Standards Department confirmed the EU ruling that the deadline for ending dual labelling had been abolished. As of 24 April 2012, there are still a few cases where imperial units are required to be used, in addition, British law specifies which non-metric units may be used with dual labelling. Numerous acts of the Saxon kings are known to have been lost and those that have survived include,2 Edgar c.3 William I c.79 Richard I c. Also the ell shall be the same in the realm and of the same length. The statutes of uncertain date are generally dated to the mid-to-late 13th century, the Assize of Bread and Ale, sometimes dated to 51 Henry III
15.
Germanic languages
–
It is the third most spoken Indo-European subdivision, behind Italic and Indo-Iranian, and ahead of Balto-Slavic languages. Limburgish varieties have roughly 1.3 million speakers along the Dutch–Belgian–German border, the main North Germanic languages are Norwegian, Danish, Swedish, Icelandic, and Faroese, which have a combined total of about 20 million speakers. The East Germanic branch included Gothic, Burgundian, and Vandalic, the last to die off was Crimean Gothic, spoken in the late 18th century in some isolated areas of Crimea. The total number of Germanic languages throughout history is unknown, as some of them—especially East Germanic languages—disappeared during or after the Migration Period. Proto-Germanic, along all of its descendants, is characterized by a number of unique linguistic features. Early varieties of Germanic enter history with the Germanic tribes moving south from Scandinavia in the 2nd century BC, to settle in the area of todays northern Germany, furthermore, it is the de facto language of the United Kingdom, the United States and Australia. It is also a language in Nicaragua and Malaysia. German is a language of Austria, Belgium, Germany, Liechtenstein, Luxembourg and Switzerland and has regional status in Italy, Poland, Namibia. German also continues to be spoken as a minority language by immigrant communities in North America, South America, Central America, Mexico, a German dialect, Pennsylvania Dutch, is still present amongst Anabaptist populations in Pennsylvania in the United States. Dutch is a language of Aruba, Belgium, Curaçao. The Netherlands also colonised Indonesia, but Dutch was scrapped as a language after Indonesian independence. Dutch was until 1925 an official language in South Africa, but evolved in and was replaced by Afrikaans, Afrikaans is one of the 11 official languages in South Africa and is a lingua franca of Namibia. It is used in other Southern African nations as well, low German is a collection of sometimes very diverse dialects spoken in the northeast of the Netherlands and northern Germany. Scots is spoken in Lowland Scotland and parts of Ulster, frisian is spoken among half a million people who live on the southern fringes of the North Sea in the Netherlands, Germany, and Denmark. Luxembourgish is mainly spoken in the Grand Duchy of Luxembourg, though it extends into small parts of Belgium, France. Limburgish varieties are spoken in the Limburg and Rhineland regions, along the Dutch–Belgian–German border, Swedish is also one of the two official languages in Finland, along with Finnish, and the only official language in the Åland Islands. Danish is also spoken natively by the Danish minority in the German state of Schleswig-Holstein, Norwegian is the official language of Norway. Icelandic is the language of Iceland, and is spoken by a significant minority in the Faroe Islands
16.
North Sea
–
The North Sea is a marginal sea of the Atlantic Ocean located between Great Britain, Scandinavia, Germany, the Netherlands, Belgium, and France. An epeiric sea on the European continental shelf, it connects to the ocean through the English Channel in the south and it is more than 970 kilometres long and 580 kilometres wide, with an area of around 570,000 square kilometres. The North Sea has long been the site of important European shipping lanes as well as a major fishery, the North Sea was the centre of the Vikings rise. Subsequently, the Hanseatic League, the Netherlands, and the British each sought to dominate the North Sea and thus the access to the markets, as Germanys only outlet to the ocean, the North Sea continued to be strategically important through both World Wars. The coast of the North Sea presents a diversity of geological and geographical features, in the north, deep fjords and sheer cliffs mark the Norwegian and Scottish coastlines, whereas in the south it consists primarily of sandy beaches and wide mudflats. Due to the population, heavy industrialization, and intense use of the sea and area surrounding it. In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean, in the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively. In the north it is bordered by the Shetland Islands, and connects with the Norwegian Sea, the North Sea is more than 970 kilometres long and 580 kilometres wide, with an area of 570,000 square kilometres and a volume of 54,000 cubic kilometres. Around the edges of the North Sea are sizeable islands and archipelagos, including Shetland, Orkney, the North Sea receives freshwater from a number of European continental watersheds, as well as the British Isles. A large part of the European drainage basin empties into the North Sea including water from the Baltic Sea, the largest and most important rivers flowing into the North Sea are the Elbe and the Rhine – Meuse watershed. Around 185 million people live in the catchment area of the rivers discharging into the North Sea encompassing some highly industrialized areas, for the most part, the sea lies on the European continental shelf with a mean depth of 90 metres. The only exception is the Norwegian trench, which extends parallel to the Norwegian shoreline from Oslo to a north of Bergen. It is between 20 and 30 kilometres wide and has a depth of 725 metres. The Dogger Bank, a vast moraine, or accumulation of unconsolidated glacial debris and this feature has produced the finest fishing location of the North Sea. The Long Forties and the Broad Fourteens are large areas with uniform depth in fathoms. These great banks and others make the North Sea particularly hazardous to navigate, the Devils Hole lies 200 miles east of Dundee, Scotland. The feature is a series of trenches between 20 and 30 kilometres long,1 and 2 kilometres wide and up to 230 metres deep. Other areas which are less deep are Cleaver Bank, Fisher Bank, the International Hydrographic Organization defines the limits of the North Sea as follows, On the Southwest
17.
Middle Ages
–
In the history of Europe, the Middle Ages or Medieval Period lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance, the Middle Ages is the middle period of the three traditional divisions of Western history, classical antiquity, the medieval period, and the modern period. The medieval period is subdivided into the Early, High. Population decline, counterurbanisation, invasion, and movement of peoples, the large-scale movements of the Migration Period, including various Germanic peoples, formed new kingdoms in what remained of the Western Roman Empire. In the seventh century, North Africa and the Middle East—once part of the Byzantine Empire—came under the rule of the Umayyad Caliphate, although there were substantial changes in society and political structures, the break with classical antiquity was not complete. The still-sizeable Byzantine Empire survived in the east and remained a major power, the empires law code, the Corpus Juris Civilis or Code of Justinian, was rediscovered in Northern Italy in 1070 and became widely admired later in the Middle Ages. In the West, most kingdoms incorporated the few extant Roman institutions, monasteries were founded as campaigns to Christianise pagan Europe continued. The Franks, under the Carolingian dynasty, briefly established the Carolingian Empire during the later 8th, the Crusades, first preached in 1095, were military attempts by Western European Christians to regain control of the Holy Land from Muslims. Kings became the heads of centralised nation states, reducing crime and violence, intellectual life was marked by scholasticism, a philosophy that emphasised joining faith to reason, and by the founding of universities. Controversy, heresy, and the Western Schism within the Catholic Church paralleled the conflict, civil strife. Cultural and technological developments transformed European society, concluding the Late Middle Ages, the Middle Ages is one of the three major periods in the most enduring scheme for analysing European history, classical civilisation, or Antiquity, the Middle Ages, and the Modern Period. Medieval writers divided history into periods such as the Six Ages or the Four Empires, when referring to their own times, they spoke of them as being modern. In the 1330s, the humanist and poet Petrarch referred to pre-Christian times as antiqua, leonardo Bruni was the first historian to use tripartite periodisation in his History of the Florentine People. Bruni and later argued that Italy had recovered since Petrarchs time. The Middle Ages first appears in Latin in 1469 as media tempestas or middle season, in early usage, there were many variants, including medium aevum, or middle age, first recorded in 1604, and media saecula, or middle ages, first recorded in 1625. The alternative term medieval derives from medium aevum, tripartite periodisation became standard after the German 17th-century historian Christoph Cellarius divided history into three periods, Ancient, Medieval, and Modern. The most commonly given starting point for the Middle Ages is 476, for Europe as a whole,1500 is often considered to be the end of the Middle Ages, but there is no universally agreed upon end date. English historians often use the Battle of Bosworth Field in 1485 to mark the end of the period
18.
Old English
–
Old English or Anglo-Saxon is the earliest historical form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers probably in the mid 5th century, Old English developed from a set of Anglo-Frisian or North Sea Germanic dialects originally spoken by Germanic tribes traditionally known as the Angles, Saxons, and Jutes. As the Anglo-Saxons became dominant in England, their language replaced the languages of Roman Britain, Common Brittonic, a Celtic language, Old English had four main dialects, associated with particular Anglo-Saxon kingdoms, Mercian, Northumbrian, Kentish and West Saxon. It was West Saxon that formed the basis for the standard of the later Old English period, although the dominant forms of Middle. The speech of eastern and northern parts of England was subject to strong Old Norse influence due to Scandinavian rule, Old English is one of the West Germanic languages, and its closest relatives are Old Frisian and Old Saxon. Like other old Germanic languages, it is different from Modern English. Old English grammar is similar to that of modern German, nouns, adjectives, pronouns, and verbs have many inflectional endings and forms. The oldest Old English inscriptions were using a runic system. Old English was not static, and its usage covered a period of 700 years, from the Anglo-Saxon settlement of Britain in the 5th century to the late 11th century, some time after the Norman invasion. While indicating that the establishment of dates is a process, Albert Baugh dates Old English from 450 to 1150, a period of full inflections. Perhaps around 85 per cent of Old English words are no longer in use, Old English is a West Germanic language, developing out of Ingvaeonic dialects from the 5th century. It came to be spoken over most of the territory of the Anglo-Saxon kingdoms which became the Kingdom of England and this included most of present-day England, as well as part of what is now southeastern Scotland, which for several centuries belonged to the Anglo-Saxon kingdom of Northumbria. Other parts of the island – Wales and most of Scotland – continued to use Celtic languages, Norse was also widely spoken in the parts of England which fell under Danish law. Anglo-Saxon literacy developed after Christianisation in the late 7th century, the oldest surviving text of Old English literature is Cædmons Hymn, composed between 658 and 680. There is a corpus of runic inscriptions from the 5th to 7th centuries. The Old English Latin alphabet was introduced around the 9th century, with the unification of the Anglo-Saxon kingdoms by Alfred the Great in the later 9th century, the language of government and literature became standardised around the West Saxon dialect. In Old English, typical of the development of literature, poetry arose before prose, a later literary standard, dating from the later 10th century, arose under the influence of Bishop Æthelwold of Winchester, and was followed by such writers as the prolific Ælfric of Eynsham. This form of the language is known as the Winchester standard and it is considered to represent the classical form of Old English
19.
Old Frisian
–
Old Frisian is a West Germanic language spoken between the 8th and 16th centuries in the area between the Rhine and Weser on the European North Sea coast. The Frisian settlers on the coast of South Jutland also spoke Old Frisian, the language of the earlier inhabitants of the region between the Zuiderzee and Ems River is attested in only a few personal names and place-names. Old Frisian evolved into Middle Frisian, spoken from the 16th to the 19th century, in the early Middle Ages, Frisia stretched from the area around Bruges, in what is now Belgium, to the Weser River in northern Germany. At the time, the Frisian language was spoken along the entire southern North Sea coast and this region is referred to as Greater Frisia or Frisia Magna, and many of the areas within it still treasure their Frisian heritage. However, by 1300, their territory had been pushed back to the Zuiderzee, hence, a close relationship exists between Old Frisian and Old English. Generally, Old Frisian phonologically resembles Old English, in particular, it shares the palatalisation of velar consonants also found in Old English. For example, whereas the closely related Old Saxon and Old Dutch retain the velar in dag, Old Frisian has dei, when followed by front vowels the Germanic /k/ changed to a /tʃ/ sound. The Old Frisian for church was tzirke or tzerke, in Old English it was ċiriċe, while Old Saxon, another feature shared between the two is Anglo-Frisian brightening, which fronted a to e under some circumstances. In unstressed syllables, o merges into a, and i into e as in Old English, the old Germanic diphthongs *ai and *au become ē/ā and ā, respectively, in Old Frisian, as in ēn/ān from Proto-Germanic *ainaz, and brād from *braudą. In comparison, these diphthongs become ā and ēa in Old English, the diphthong *eu generally becomes ia, and Germanic *iu is retained. These diphthongs initially began with a i, but the stress later shifts to the second component, giving to iā. For example, thiād and liūde from Proto-Germanic *þeudō and *liudīz, between vowels, h generally disappears, as in Old English and Old Dutch. Word-initial h- on the hand is retained. Some of the texts that are preserved from this period are from the 12th or 13th centuries, generally, all these texts are restricted to legal writings. These runic writings however usually consist of no more than inscriptions of a single or few words, amsterdam and Philadelphia, John Benjamins,2009. They show a degree of linguistic uniformity. Westeremden yew-stick Fon Alra Fresena Fridome Hunsigo MSS H1, H2, Ten Commandements,17 petitiones Londriucht Thet Freske Riim Skeltana Riucht law code
20.
Old High German
–
Old High German is the earliest stage of the German language, conventionally covering the period from around 700 to 1050. Coherent written texts do not appear until the half of the 8th century. There are, however, a number of Elder Futhark inscriptions dating to the 6th century, as well as single words, during the migration period, the Elbe Germanic tribes settled in what became Alamannia, the Duchy of Bavaria and the Kingdom of Lombardy. Old High German comprises the dialects of these groups which underwent the Second Sound Shift during the 6th Century, namely all of Elbe Germanic, in the south, the Langobards, who had settled in Northern Italy, maintained their dialect until their conquest by Charlemagne in 774. This area did not become German-speaking again until the German eastward expansion of the early 12th century, though there was some attempt at conquest, Old High German literacy is a product of the monasteries, notably at St. Gallen, Reichenau and Fulda. Its origins lie in the establishment of the German church by Boniface in the mid 8th century, einhard tells how Charlemagne himself ordered that the epic lays should be collected for posterity. It was the neglect or religious zeal of later generations that led to the loss of these records, thus, it was Charlemagnes weak successor, Louis the Pious, who destroyed his fathers collection of epic poetry on account of its pagan content. Hrabanus Maurus, a student of Alcuins and abbot at Fulda from 822, was an important advocate of the cultivation of German literacy, among his students were Walafrid Strabo and Otfrid of Weissenburg. Notker Labeo towards the end of the Old High German period was among the greatest stylists in the language, the main difference between Old High German and the West Germanic dialects from which it developed is that it underwent the High German consonant shift. This is generally dated approximately to the late 5th and early 6th centuries—hence dating its start to around 500, the result of this sound change is that the consonantal system of German remains different from all other West Germanic languages, including English and Low German. Grammatically, however, Old High German remained very similar to Old English, Old Dutch, by the mid 11th century the many different vowels found in unstressed syllables had all been reduced to /ə/. Since these vowels were part of the endings in the nouns and verbs. For these reasons,1050 is seen as the start of the Middle High German period, for this reason the dialects may be termed monastery dialects. It declined after the conquest of the Lombard Kingdom by the Franks in 774 and it is classified as Upper German on the basis of evidence of the Second Sound Shift. The continued existence of a West Frankish dialect in the Western, claims that this might have been the language of the Carolingian court or that it is attested in the Ludwigslied, whose presence in a French manuscript suggests bilingualism, are controversial. The charts show the vowel and consonant systems of the East Franconian dialect in the 9th century and this is the dialect of the monastery of Fulda, and specifically of the Old High German Tatian. Old High German had five long vowels and six phonemic short vowels. Both occurred in stressed and unstressed syllables, notes, All back vowels likely had front-vowel allophones as a result of Umlaut
21.
Medieval Latin
–
Despite the clerical origin of many of its authors, medieval Latin should not be confused with Ecclesiastical Latin. There is no consensus on the exact boundary where Late Latin ends. Medieval Latin had a vocabulary, which freely borrowed from other sources. Greek provided much of the vocabulary of Christianity. The various Germanic languages spoken by the Germanic tribes, who invaded southern Europe, were major sources of new words. Germanic leaders became the rulers of parts of the Roman Empire that they conquered, other more ordinary words were replaced by coinages from Vulgar Latin or Germanic sources because the classical words had fallen into disuse. Latin was also spread to such as Ireland and Germany. Works written in the lands, where Latin was a language with no relation to the local vernacular, also influenced the vocabulary. English words like abstract, subject, communicate, matter, probable, the high point of the development of medieval Latin as a literary language came with the Carolingian renaissance, a rebirth of learning kindled under the patronage of Charlemagne, king of the Franks. On the other hand, strictly speaking there was no form of medieval Latin. Every Latin author in the period spoke Latin as a second language, with varying degrees of fluency, and syntax, grammar. For instance, rather than following the classical Latin practice of placing the verb at the end. Unlike classical Latin, where esse was the auxiliary verb, medieval Latin writers might use habere as an auxiliary, similar to constructions in Germanic. The accusative and infinitive construction in classical Latin was often replaced by a clause introduced by quod or quia. This is almost identical, for example, to the use of que in similar constructions in French. In every age from the late 8th century onwards, there were learned writers who were familiar enough with classical syntax to be aware that these forms and usages were wrong, however the use of quod to introduce subordinate clauses was especially pervasive and is found at all levels. That resulted in two features of Medieval Latin compared with Classical Latin. First, many attempted to show off their knowledge of Classical Latin by using rare or archaic constructions
22.
German language
–
German is a West Germanic language that is mainly spoken in Central Europe. It is the most widely spoken and official language in Germany, Austria, Switzerland, South Tyrol, the German-speaking Community of Belgium and it is also one of the three official languages of Luxembourg. Major languages which are most similar to German include other members of the West Germanic language branch, such as Afrikaans, Dutch, English, Luxembourgish and it is the second most widely spoken Germanic language, after English. One of the languages of the world, German is the first language of about 95 million people worldwide. The German speaking countries are ranked fifth in terms of publication of new books. German derives most of its vocabulary from the Germanic branch of the Indo-European language family, a portion of German words are derived from Latin and Greek, and fewer are borrowed from French and English. With slightly different standardized variants, German is a pluricentric language, like English, German is also notable for its broad spectrum of dialects, with many unique varieties existing in Europe and also other parts of the world. The history of the German language begins with the High German consonant shift during the migration period, when Martin Luther translated the Bible, he based his translation primarily on the standard bureaucratic language used in Saxony, also known as Meißner Deutsch. Copies of Luthers Bible featured a long list of glosses for each region that translated words which were unknown in the region into the regional dialect. Roman Catholics initially rejected Luthers translation, and tried to create their own Catholic standard of the German language – the difference in relation to Protestant German was minimal. It was not until the middle of the 18th century that a widely accepted standard was created, until about 1800, standard German was mainly a written language, in urban northern Germany, the local Low German dialects were spoken. Standard German, which was different, was often learned as a foreign language with uncertain pronunciation. Northern German pronunciation was considered the standard in prescriptive pronunciation guides though, however, German was the language of commerce and government in the Habsburg Empire, which encompassed a large area of Central and Eastern Europe. Until the mid-19th century, it was essentially the language of townspeople throughout most of the Empire and its use indicated that the speaker was a merchant or someone from an urban area, regardless of nationality. Some cities, such as Prague and Budapest, were gradually Germanized in the years after their incorporation into the Habsburg domain, others, such as Pozsony, were originally settled during the Habsburg period, and were primarily German at that time. Prague, Budapest and Bratislava as well as cities like Zagreb, the most comprehensive guide to the vocabulary of the German language is found within the Deutsches Wörterbuch. This dictionary was created by the Brothers Grimm and is composed of 16 parts which were issued between 1852 and 1860, in 1872, grammatical and orthographic rules first appeared in the Duden Handbook. In 1901, the 2nd Orthographical Conference ended with a standardization of the German language in its written form
23.
French language
–
French is a Romance language of the Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages, French has evolved from Gallo-Romance, the spoken Latin in Gaul, and more specifically in Northern Gaul. Its closest relatives are the other langues doïl—languages historically spoken in northern France and in southern Belgium, French was also influenced by native Celtic languages of Northern Roman Gaul like Gallia Belgica and by the Frankish language of the post-Roman Frankish invaders. Today, owing to Frances past overseas expansion, there are numerous French-based creole languages, a French-speaking person or nation may be referred to as Francophone in both English and French. French is a language in 29 countries, most of which are members of la francophonie. As of 2015, 40% of the population is in Europe, 35% in sub-Saharan Africa, 15% in North Africa and the Middle East, 8% in the Americas. French is the fourth-most widely spoken mother tongue in the European Union, 1/5 of Europeans who do not have French as a mother tongue speak French as a second language. As a result of French and Belgian colonialism from the 17th and 18th century onward, French was introduced to new territories in the Americas, Africa, most second-language speakers reside in Francophone Africa, in particular Gabon, Algeria, Mauritius, Senegal and Ivory Coast. In 2015, French was estimated to have 77 to 110 million native speakers, approximately 274 million people are able to speak the language. The Organisation internationale de la Francophonie estimates 700 million by 2050, in 2011, Bloomberg Businessweek ranked French the third most useful language for business, after English and Standard Mandarin Chinese. Under the Constitution of France, French has been the language of the Republic since 1992. France mandates the use of French in official government publications, public education except in specific cases, French is one of the four official languages of Switzerland and is spoken in the western part of Switzerland called Romandie, of which Geneva is the largest city. French is the language of about 23% of the Swiss population. French is also a language of Luxembourg, Monaco, and Aosta Valley, while French dialects remain spoken by minorities on the Channel Islands. A plurality of the worlds French-speaking population lives in Africa and this number does not include the people living in non-Francophone African countries who have learned French as a foreign language. Due to the rise of French in Africa, the total French-speaking population worldwide is expected to reach 700 million people in 2050, French is the fastest growing language on the continent. French is mostly a language in Africa, but it has become a first language in some urban areas, such as the region of Abidjan, Ivory Coast and in Libreville. There is not a single African French, but multiple forms that diverged through contact with various indigenous African languages, sub-Saharan Africa is the region where the French language is most likely to expand, because of the expansion of education and rapid population growth
24.
Imperial units
–
The system of imperial units or the imperial system is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced. The Imperial units replaced the Winchester Standards, which were in effect from 1588 to 1825, the system came into official use across the British Empire. The imperial system developed from what were first known as English units, the Weights and Measures Act of 1824 was initially scheduled to go into effect on 1 May 1825. However, the Weights and Measures Act of 1825 pushed back the date to 1 January 1826, the 1824 Act allowed the continued use of pre-imperial units provided that they were customary, widely known, and clearly marked with imperial equivalents. Apothecaries units are mentioned neither in the act of 1824 nor 1825, at the time, apothecaries weights and measures were regulated in England, Wales, and Berwick-upon-Tweed by the London College of Physicians, and in Ireland by the Dublin College of Physicians. In Scotland, apothecaries units were unofficially regulated by the Edinburgh College of Physicians, the three colleges published, at infrequent intervals, pharmacopoeiae, the London and Dublin editions having the force of law. The Medical Act of 1858 transferred to The Crown the right to publish the official pharmacopoeia and to regulate apothecaries weights, Metric equivalents in this article usually assume the latest official definition. Before this date, the most precise measurement of the imperial Standard Yard was 0.914398416 metres, in 1824, the various different gallons in use in the British Empire were replaced by the imperial gallon, a unit close in volume to the ale gallon. It was originally defined as the volume of 10 pounds of distilled water weighed in air with brass weights with the standing at 30 inches of mercury at a temperature of 62 °F. The Weights and Measures Act of 1985 switched to a gallon of exactly 4.54609 l and these measurements were in use from 1826, when the new imperial gallon was defined, but were officially abolished in the United Kingdom on 1 January 1971. In the USA, though no longer recommended, the system is still used occasionally in medicine. The troy pound was made the unit of mass by the 1824 Act, however, its use was abolished in the UK on 1 January 1879, with only the troy ounce. The Weights and Measures Act 1855 made the pound the primary unit of mass. In all the systems, the unit is the pound. For the yard, the length of a pendulum beating seconds at the latitude of Greenwich at Mean Sea Level in vacuo was defined as 39.01393 inches, the imperial system is one of many systems of English units. Although most of the units are defined in more than one system, some units were used to a much greater extent, or for different purposes. The distinctions between these systems are not drawn precisely. One such distinction is that between these systems and older British/English units/systems or newer additions, the US customary system is historically derived from the English units that were in use at the time of settlement
25.
United States customary units
–
United States customary units are a system of measurements commonly used in the United States. The United States customary system developed from English units which were in use in the British Empire before the US declared its independence, however, the British system of measures was overhauled in 1824 to create the imperial system, changing the definitions of some units. Therefore, while many U. S. units are similar to their Imperial counterparts. The majority of U. S. customary units were redefined in terms of the meter and these definitions were refined by the international yard and pound agreement of 1959. Americans primarily use customary units in commercial activities, as well as for personal and social use, in science, medicine, many sectors of industry and some of government, metric units are used. The International System of Units, the form of the metric system, is preferred for many uses by the U. S. National Institute of Standards. The United States system of units is similar to the British imperial system, both systems are derived from English units, a system which had evolved over the millennia before American independence, and which had its roots in Roman and Anglo-Saxon units. The customary system was championed by the U. S. -based International Institute for Preserving and Perfecting Weights, advocates of the customary system saw the French Revolutionary, or metric, system as atheistic. An auxiliary of the Institute in Ohio published a poem with wording such as down with every metric scheme and A perfect inch, one adherent of the customary system called it a just weight and a just measure, which alone are acceptable to the Lord. The U. S. government passed the Metric Conversion Act of 1975, the legislation states that the federal government has a responsibility to assist industry as it voluntarily converts to the metric system, i. e. metrification. This is most evident in U. S. labeling requirements on food products, according to the CIA Factbook, the United States is one of three nations that have not adopted the metric system as their official system of weights and measures. U. S. customary units are used on consumer products. Metric units are standard in science, medicine, as well as many sectors of industry and government, the metric system also lacks a parallel to the foot. Frequently, however, these units designate quite different sizes, for example, the mile ranged by country from one-half to five U. S. miles, foot and pound also had varying definitions. Historically, a range of non-SI units were used in the U. S. and in Britain. This article deals only with the commonly used or officially defined in the U. S. For measuring length, the U. S. customary system uses the inch, foot, yard, and mile, since July 1,1959, these have been defined on the basis of 1 yard =0.9144 meters except for some applications in surveying. The U. S. the United Kingdom and other Commonwealth countries agreed on this definition, the NAD27 was replaced in the 1980s by the North American Datum of 1983, which is defined in meters
26.
Orders of magnitude (mass)
–
To help compare different orders of magnitude, the following lists describe various mass levels between 10−40 kg and 1053 kg. The table below is based on the kilogram, the unit of mass in the International System of Units. The kilogram is the standard unit to include an SI prefix as part of its name. The gram is an SI derived unit of mass, however, the names of all SI mass units are based on gram, rather than on kilogram, thus 103 kg is a megagram, not a kilokilogram. The tonne is a SI-compatible unit of equal to a megagram. The unit is in use for masses above about 103 kg and is often used with SI prefixes. Other units of mass are also in use, historical units include the stone, the pound, the carat, and the grain. For subatomic particles, physicists use the equivalent to the energy represented by an electronvolt. At the atomic level, chemists use the mass of one-twelfth of a carbon-12 atom, astronomers use the mass of the sun. Unlike other physical quantities, mass-energy does not have an a priori expected minimal quantity, as is the case with time or length, plancks law allows for the existence of photons with arbitrarily low energies. This series on orders of magnitude does not have a range of larger masses Mass units conversion calculator Mass units conversion calculator JavaScript
27.
Trillion (short scale)
–
This list contains selected positive numbers in increasing order, including counts of things, dimensionless quantity and probabilities. Mathematics – Writing, Approximately 10−183,800 is a rough first estimate of the probability that a monkey, however, taking punctuation, capitalization, and spacing into account, the actual probability is far lower, around 10−360,783. Computing, The number 1×10−6176 is equal to the smallest positive non-zero value that can be represented by a quadruple-precision IEEE decimal floating-point value, Computing, The number 6. 5×10−4966 is approximately equal to the smallest positive non-zero value that can be represented by a quadruple-precision IEEE floating-point value. Computing, The number 3. 6×10−4951 is approximately equal to the smallest positive non-zero value that can be represented by a 80-bit x86 double-extended IEEE floating-point value. Computing, The number 1×10−398 is equal to the smallest positive non-zero value that can be represented by a double-precision IEEE decimal floating-point value, Computing, The number 4. 9×10−324 is approximately equal to the smallest positive non-zero value that can be represented by a double-precision IEEE floating-point value. Computing, The number 1×10−101 is equal to the smallest positive non-zero value that can be represented by a single-precision IEEE decimal floating-point value, Mathematics, The probability in a game of bridge of all four players getting a complete suit is approximately 4. 47×10−28. ISO, yocto- ISO, zepto- Mathematics, The probability of matching 20 numbers for 20 in a game of keno is approximately 2.83 × 10−19. ISO, atto- Mathematics, The probability of rolling snake eyes 10 times in a row on a pair of dice is about 2. 74×10−16. ISO, micro- Mathematics – Poker, The odds of being dealt a flush in poker are 649,739 to 1 against. Mathematics – Poker, The odds of being dealt a flush in poker are 72,192 to 1 against. Mathematics – Poker, The odds of being dealt a four of a kind in poker are 4,164 to 1 against, for a probability of 2.4 × 10−4. ISO, milli- Mathematics – Poker, The odds of being dealt a full house in poker are 693 to 1 against, for a probability of 1.4 × 10−3. Mathematics – Poker, The odds of being dealt a flush in poker are 507.8 to 1 against, Mathematics – Poker, The odds of being dealt a straight in poker are 253.8 to 1 against, for a probability of 4 × 10−3. Physics, α =0.007297352570, the fine-structure constant, ISO, deci- Mathematics – Poker, The odds of being dealt only one pair in poker are about 5 to 2 against, for a probability of 0.42. Demography, The population of Monowi, a village in Nebraska. Mathematics, √2 ≈1.414213562373095489, the ratio of the diagonal of a square to its side length. Mathematics, φ ≈1.618033988749895848, the golden ratio Mathematics, the number system understood by most computers, human scale, There are 10 digits on a pair of human hands, and 10 toes on a pair of human feet. Mathematics, The number system used in life, the decimal system, has 10 digits,0,1,2,3,4,5,6,7,8,9
28.
Long and short scales
–
Thus, billion means a million millions, trillion means a million billions, and so on. Short scale Every new term greater than million is one thousand times larger than the previous term, thus, billion means a thousand millions, trillion means a thousand billions, and so on. For whole numbers less than a million the two scales are identical. From a thousand million up the two scales diverge, using the words for different numbers, this can cause misunderstanding. Countries where the scale is currently used include most countries in continental Europe and most French-speaking, Spanish-speaking. The short scale is now used in most English-speaking and Arabic-speaking countries, in Brazil, in former Soviet Union, number names are rendered in the language of the country, but are similar everywhere due to shared etymology. Some languages, particularly in East Asia and South Asia, have large number naming systems that are different from both the long and short scales, for example the Indian numbering system. After several decades of increasing informal British usage of the scale, in 1974 the government of the UK adopted it. With very few exceptions, the British usage and American usage are now identical, the first recorded use of the terms short scale and long scale was by the French mathematician Geneviève Guitel in 1975. At and above a million the same names are used to refer to numbers differing by a factor of an integer power of 1,000. Each scale has a justification to explain the use of each such differing numerical name. The short-scale logic is based on powers of one thousand, whereas the long-scale logic is based on powers of one million, in both scales, the prefix bi- refers to 2 and tri- refers to 3, etc. However only in the scale do the prefixes beyond one million indicate the actual power or exponent. In the short scale, the prefixes refer to one less than the exponent, the word, million, derives from the Old French, milion, from the earlier Old Italian, milione, an intensification of the Latin word, mille, a thousand. That is, a million is a big thousand, much as a great gross is a dozen gross or 12×144 =1728, the word, milliard, or its translation, is found in many European languages and is used in those languages for 109. However, it is unknown in American English, which uses billion, and not used in British English, which preferred to use thousand million before the current usage of billion. The financial term, yard, which derives from milliard, is used on financial markets, as, unlike the term, billion, it is internationally unambiguous and phonetically distinct from million. Likewise, many long scale use the word billiard for one thousand long scale billions
29.
Knot (unit)
–
The knot is a unit of speed equal to one nautical mile per hour, approximately 1.151 mph. The ISO Standard symbol for the knot is kn, the same symbol is preferred by the IEEE, kt is also common. The knot is a unit that is accepted for use with the SI. Etymologically, the term derives from counting the number of knots in the line that unspooled from the reel of a log in a specific time. 1 international knot =1 nautical mile per hour,1.852 kilometres per hour,0.514 metres per second,1.151 miles per hour,20.254 inches per second,1852 m is the length of the internationally agreed nautical mile. The US adopted the definition in 1954, having previously used the US nautical mile. The UK adopted the international nautical mile definition in 1970, having used the UK Admiralty nautical mile. The speeds of vessels relative to the fluids in which they travel are measured in knots, for consistency, the speeds of navigational fluids are also measured in knots. Thus, speed over the ground and rate of progress towards a distant point are given in knots. Until the mid-19th century, vessel speed at sea was measured using a chip log, the chip log was cast over the stern of the moving vessel and the line allowed to pay out. Knots placed at a distance of 8 fathoms -47 feet 3 inches from each other, passed through a sailors fingers, the knot count would be reported and used in the sailing masters dead reckoning and navigation. This method gives a value for the knot of 20.25 in/s, the difference from the modern definition is less than 0. 02%. On a chart of the North Atlantic, the scale varies by a factor of two from Florida to Greenland, a single graphic scale, of the sort on many maps, would therefore be useless on such a chart. Recent British Admiralty charts have a latitude scale down the middle to make this even easier, speed is sometimes incorrectly expressed as knots per hour, which is in fact a measure of acceleration. Prior to 1969, airworthiness standards for aircraft in the United States Federal Aviation Regulations specified that distances were to be in statute miles. In 1969, these standards were amended to specify that distances were to be in nautical miles. At 11000 m, an airspeed of 300 kn may correspond to a true airspeed of 500 kn in standard conditions. Beaufort scale Hull speed, which deals with theoretical estimates of maximum speed of displacement hulls Knot count Knotted cord Metre per second Orders of magnitude Rope Kemp
30.
Metric ton unit
–
The SI symbol for the tonne is t, adopted at the same time as the unit itself in 1879. Its use is also official, for the metric ton, within the United States, having been adopted by the US National Institute of Standards and it is a symbol, not an abbreviation, and should not be followed by a period. Informal and non-approved symbols or abbreviations include T, mT, MT, in French and all English-speaking countries that are predominantly metric, tonne is the correct spelling. Before metrication in the UK the unit used for most purposes was the Imperial ton of 2,240 pounds avoirdupois, equivalent to 1,016 kg, differing by just 1. 6% from the tonne. Ton and tonne are both derived from a Germanic word in use in the North Sea area since the Middle Ages to designate a large cask. A full tun, standing about a high, could easily weigh a tonne. An English tun of wine weighs roughly a tonne,954 kg if full of water, in the United States, the unit was originally referred to using the French words millier or tonneau, but these terms are now obsolete. The Imperial and US customary units comparable to the tonne are both spelled ton in English, though they differ in mass, one tonne is equivalent to, Metric/SI,1 megagram. Equal to 1000000 grams or 1000 kilograms, megagram, Mg, is the official SI unit. Mg is distinct from mg, milligram, pounds, Exactly 1000/0. 453 592 37 lb, or approximately 2204.622622 lb. US/Short tons, Exactly 1/0. 907 184 74 short tons, or approximately 1.102311311 ST. One short ton is exactly 0.90718474 t, imperial/Long tons, Exactly 1/1. 016 046 9088 long tons, or approximately 0.9842065276 LT. One long ton is exactly 1.0160469088 t, for multiples of the tonne, it is more usual to speak of thousands or millions of tonnes. Kilotonne, megatonne, and gigatonne are more used for the energy of nuclear explosions and other events. When used in context, there is little need to distinguish between metric and other tons, and the unit is spelt either as ton or tonne with the relevant prefix attached. *The equivalent units columns use the short scale large-number naming system used in most English-language countries. †Values in the equivalent short and long tons columns are rounded to five significant figures, ǂThough non-standard, the symbol kt is also sometimes used for knot, a unit of speed for sea-going vessels, and should not be confused with kilotonne. A metric ton unit can mean 10 kilograms within metal trading and it traditionally referred to a metric ton of ore containing 1% of metal. In the case of uranium, the acronym MTU is sometimes considered to be metric ton of uranium, in the petroleum industry the tonne of oil equivalent is a unit of energy, the amount of energy released by burning one tonne of crude oil, approximately 42 GJ
31.
Uranium
–
Uranium is a chemical element with symbol U and atomic number 92. It is a metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons, Uranium is weakly radioactive because all its isotopes are unstable. The most common isotopes in natural uranium are uranium-238 and uranium-235, Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and it occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238, uranium-235, Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years, many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 is the naturally occurring fissile isotope, which makes it widely used in nuclear power plants. However, because of the amounts found in nature, uranium needs to undergo enrichment so that enough uranium-235 is present. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor, another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. In sufficient concentration, these maintain a sustained nuclear chain reaction. This generates the heat in nuclear reactors, and produces the fissile material for nuclear weapons. Depleted uranium is used in kinetic energy penetrators and armor plating, Uranium is used as a colorant in uranium glass, producing lemon yellow to green colors. Uranium glass fluoresces green in ultraviolet light and it was also used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, eugène-Melchior Péligot was the first person to isolate the metal and its radioactive properties were discovered in 1896 by Henri Becquerel. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of weapons that used uranium metal. The security of those weapons and their fissile material following the breakup of the Soviet Union in 1991 is a concern for public health. When refined, uranium is a white, weakly radioactive metal
32.
Intergovernmental Panel on Climate Change
–
Membership of the IPCC is open to all members of the WMO and UNEP. The IPCC produces reports that support the United Nations Framework Convention on Climate Change, the ultimate objective of the UNFCCC is to stabilize greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. The IPCC does not carry out its own research, nor does it do the work of monitoring climate or related phenomena itself. The IPCC bases its assessment on the literature, which includes peer-reviewed and non-peer-reviewed sources. Thousands of scientists and other experts contribute to writing and reviewing reports, IPCC reports contain a Summary for Policymakers, which is subject to line-by-line approval by delegates from all participating governments. Typically this involves the governments of more than 120 countries, the IPCC provides an internationally accepted authority on climate change, producing reports which have the agreement of leading climate scientists and the consensus of participating governments. The 2007 Nobel Peace Prize was shared, in equal parts, in this way, it was formed as a hybrid between a scientific body and an intergovernmental political organisation. The aims of the IPCC are to assess scientific information relevant to, Human-induced climate change, The impacts of human-induced climate change, korean economist Hoesung Lee has been the chair of the IPCC since October 8,2015, following the election of the new IPCC Bureau. Before this election, the IPCC was led by his vice-Chair Ismail El Gizouli, the previous chairs were Rajendra K. Pachauri, elected in May 2002, Robert Watson in 1997, and Bert Bolin in 1988. The chair is assisted by an elected bureau including vice-chairs, working group co-chairs, the IPCC Panel is composed of representatives appointed by governments and organizations. Participation of delegates with appropriate expertise is encouraged, plenary sessions of the IPCC and IPCC Working groups are held at the level of government representatives. Non Governmental and Intergovernmental Organizations may be allowed to attend as observers, Sessions of the IPCC Bureau, workshops, expert and lead authors meetings are by invitation only. Attendance at the 2003 meeting included 350 government officials and climate change experts, after the opening ceremonies, closed plenary sessions were held. The meeting report states there were 322 persons in attendance at Sessions with about seven-eighths of participants being from governmental organizations, there are several major groups, IPCC Panel, Meets in plenary session about once a year and controls the organizations structure, procedures, and work program. The Panel is the IPCC corporate entity, Secretariat, Oversees and manages all activities. 30 members include IPCC Vice-Chairs, Co-Chairs and Vice-Chairs of Working Groups, Working Groups, Each has two Co-Chairs, one from the developed and one from developing world, and a technical support unit. Working Group I, Assesses scientific aspects of the climate system, Co-Chairs, Valérie Masson-Delmotte and Panmao Zhai Working Group II, Assesses vulnerability of socio-economic and natural systems to climate change, consequences, and adaptation options. Co-Chairs, Hans-Otto Pörtner and Debra Roberts Working Group III, Assesses options for limiting greenhouse gas emissions, the organisation is required to comply with the Financial Regulations and Rules of the WMO
33.
Global warming
–
Global warming and climate change are terms for the observed century-scale rise in the average temperature of the Earths climate system and its related effects. Multiple lines of evidence show that the climate system is warming. The largest human influence has been emission of gases such as carbon dioxide, methane. These findings have been recognized by the science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing. Future climate change and associated impacts will differ from region to region around the globe, anticipated effects include warming global temperature, rising sea levels, changing precipitation, and expansion of deserts in the subtropics. Warming is expected to be greater over land than over the oceans and greatest in the Arctic, with the retreat of glaciers, permafrost. Effects significant to humans include the threat to security from decreasing crop yields. Possible societal responses to global warming include mitigation by emissions reduction, adaptation to its effects, building systems resilient to its effects, most countries are parties to the United Nations Framework Convention on Climate Change, whose ultimate objective is to prevent dangerous anthropogenic climate change. Public reactions to global warming and concern about its effects are also increasing, a global 2015 Pew Research Center report showed a median of 54% consider it a very serious problem. There are significant regional differences, with Americans and Chinese among the least concerned, the global average surface temperature shows a warming of 0.85 °C in the period 1880 to 2012, based on multiple independently produced datasets. Earths average surface temperature rose by 0. 74±0.18 °C over the period 1906–2005, the rate of warming almost doubled for the last half of that period. The rest has melted ice and warmed the continents and atmosphere, the average temperature of the lower troposphere has increased between 0.12 and 0.135 °C per decade since 1979, according to satellite temperature measurements. The warming that is evident in the temperature record is consistent with a wide range of observations. The probability that these changes could have occurred by chance is virtually zero, temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures, ocean temperatures increase more slowly than land temperatures because of the larger effective heat capacity of the oceans and because the ocean loses more heat by evaporation. Since the beginning of industrialisation the temperature difference between the hemispheres has increased due to melting of sea ice and snow in the North. Average arctic temperatures have been increasing at almost twice the rate of the rest of the world in the past 100 years, the thermal inertia of the oceans and slow responses of other indirect effects mean that climate can take centuries or longer to adjust to changes in forcing. Some of this warming will be driven by past natural forcings which are still seeking equilibrium in the climate system
34.
TNT
–
Trinitrotoluene, or more specifically 2,4, 6-trinitrotoluene, is a chemical compound with the formula C6H23CH3. This yellow-colored solid is used as a reagent in chemical synthesis. The explosive yield of TNT is considered to be the measure of bombs. In chemistry, TNT is used to charge transfer salts. TNT was first prepared in 1863 by German chemist Julius Wilbrand and its potential as an explosive was not appreciated for several years, mainly because it was so difficult to detonate and because it was less powerful than alternatives. Its explosive properties were first discovered by another German chemist, Carl Häussermann, the German armed forces adopted it as a filling for artillery shells in 1902. The British started replacing lyddite with TNT in 1907, TNT is still widely used by the United States military, as well as construction companies around the world. The majority of TNT currently used by the US military is manufactured by Radford Army Ammunition Plant near Radford, in industry, TNT is produced in a three-step process. First, toluene is nitrated with a mixture of sulfuric and nitric acid to produce mononitrotoluene, the MNT is separated and then renitrated to dinitrotoluene. In the final step, the DNT is nitrated to trinitrotoluene using a mixture of nitric acid. Nitric acid is consumed by the process, but the diluted sulfuric acid can be reconcentrated and reused. The rinse water from sulphitation is known as red water and is a significant pollutant, control of nitrogen oxides in feed nitric acid is very important because free nitrogen dioxide can result in oxidation of the methyl group of toluene. This reaction is exothermic and carries with it the risk of a runaway reaction leading to an explosion. In the laboratory,2,4, 6-trinitrotoluene is produced by a two-step process, a nitrating mixture of concentrated nitric and sulfuric acids is used to nitrate toluene to a mixture of mono- and di-nitrotoluene isomers, with careful cooling to maintain temperature. The nitrated toluenes are then separated, washed with dilute sodium bicarbonate to remove oxides of nitrogen, towards the end of the nitration, the mixture is heated on a steam bath. The trinitrotoluene is separated, washed with a solution of sodium sulfite. TNT is one of the most commonly used explosives for military, industrial, TNT has been used in conjunction with hydraulic fracturing, a process used to recover oil and gas from shale formations. The technique involves displacing and detonating nitroglycerin in hydraulically induced fractures followed by wellbore shots using pelletized TNT, TNT is valued partly because of its insensitivity to shock and friction, with reduced risk of accidental detonation compared to more sensitive explosives such as nitroglycerin
35.
Explosive material
–
An explosive charge is a measured quantity of explosive material, which may be composed of a single ingredient or a combination of two or more. Materials that detonate are said to be high explosives and materials that deflagrate are said to be low explosives, Explosives may also be categorized by their sensitivity. Sensitive materials that can be initiated by a small amount of heat or pressure are primary explosives. A wide variety of chemicals can explode, a number are manufactured specifically for the purpose of being used as explosives. The remainder are too dangerous, sensitive, toxic, expensive, unstable, in contrast, some materials are merely combustible or flammable if they burn without exploding. The distinction, however, is not razor-sharp, though early thermal weapons, such as Greek fire, have existed since ancient times, the first widely used explosive in warfare and mining was black powder, invented in 9th century China. This material was sensitive to water, and it produced copious amounts of dark smoke, the first useful explosive stronger than black powder was nitroglycerin, developed in 1847. Since nitroglycerin is a liquid and highly unstable, it was replaced by nitrocellulose, TNT in 1863, smokeless powder, dynamite in 1867, World War I saw the adoption of TNT trinitrotoluene in artillery shells. World War II saw a use of new explosives. In turn, these have largely replaced by more powerful explosives such as C-4. However, C-4 and PETN react with metal and catch fire easily, yet unlike TNT, C-4 and PETN are waterproof, the largest commercial application of explosives is mining. In Materials Science and Engineering, explosives are used in cladding, a thin plate of some material is placed atop a thick layer of a different material, both layers typically of metal. Atop the thin layer is placed an explosive, at one end of the layer of explosive, the explosion is initiated. The two metallic layers are forced together at high speed and with great force, the explosion spreads from the initiation site throughout the explosive. Ideally, this produces a metallurgical bond between the two layers and it is possible that some fraction of the surface material from either layer eventually gets ejected when the end of material is reached. Hence, the mass of the now welded bilayer, may be less than the sum of the masses of the two initial layers, there are applications where a shock wave, and electrostatics, can result in high velocity projectiles. Thus, explosives are substances that contain an amount of energy stored in chemical bonds. Consequently, most commercial explosives are compounds containing -NO2, -ONO2 and -NHNO2 groups that
36.
Nuclear weapon yield
–
An explosive yield of one terajoule is 0.239 kt of TNT. The yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon, the practical maximum yield-to-weight ratio for fusion weapons has been estimated to six megatons of TNT per metric ton of bomb mass. Yields of 5.2 megatons/ton and higher have been reported for large weapons constructed for use in the early 1960s. Most artificial non-nuclear explosions are considerably smaller than even what are considered to be very small nuclear weapons, the yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon. According to nuclear-weapons designer Ted Taylor, the practical maximum yield-to-weight ratio for fusion weapons is about 6 megatons of TNT per metric ton. The Taylor limit is not derived from first principles, and weapons with yields as high as 9.5 megatons per metric ton have been designed and built. The 25 Mt yield option reported for the B41 would give it a ratio of 5.1 megatons of TNT per metric ton. This results in the B41 still retaining the record for the highest Yield-to-weight weapon ever designed, in 1963 DOE declassified statements that the U. S. had the technological capability of deploying a 35 Mt warhead on the Titan II, or a 50-60 Mt gravity bomb on B-52s. Neither weapon was pursued, but either would require yield-to-weight ratios superior to a 25 Mt Mk-41, for current smaller US weapons, yield is 600 to 2200 kilotons of TNT per metric ton. By comparison, for the very small devices such as the Davy Crockett it was 0.4 to 40 kilotons of TNT per metric ton. For historical comparison, for Little Boy the yield was only 4 kilotons of TNT per metric ton, and for the largest Tsar Bomba, the yield was 2 megatons of TNT per metric ton. The largest pure-fission bomb ever constructed Ivy King had a 500 kiloton yield, however, there is no known upper yield limit for a fusion bomb. For example, the Mk-36 bomb as built had a ratio of 1.25 megatons of TNT per metric ton. Delivery size limits can be estimated to ascertain limits to delivery of high yield weapons. If the full 250 metric ton payload of the Antonov An-225 aircraft could be used, likewise, the maximum limit of a missile-delivered weapon is determined by the missile gross payload capacity. The large Russian SS-18 ICBM has a capacity of 7,200 kg. A Saturn V-scale missile could deliver over 120 tons, giving a maximum yield of about 700 megatons. The following list is of nuclear explosions
37.
Energy density
–
Energy density is the amount of energy stored in a given system or region of space per unit volume. Colloquially it may also be used for energy per unit mass, often only the useful or extractable energy is measured, which is to say that chemically inaccessible energy such as rest mass energy is ignored. In short, pressure is a measure of the enthalpy per unit volume of a system, a pressure gradient has a potential to perform work on the surroundings by converting enthalpy until equilibrium is reached. There are many different types of stored in materials. In order of the magnitude of the energy released, these types of reactions are, nuclear, chemical, electrochemical. Chemical reactions are used by animals to derive energy from food, electrochemical reactions are used by most mobile devices such as laptop computers and mobile phones to release the energy from batteries. The following is a list of the energy densities of commonly used or well-known energy storage materials. Note that this list does not consider the mass of reactants commonly available such as the oxygen required for combustion or the efficiency in use. The following unit conversions may be helpful when considering the data in the table,1 MJ ≈0.28 kWh ≈0.37 HPh. In energy storage applications the energy density relates the mass of a store to the volume of the storage facility. The higher the density of the fuel, the more energy may be stored or transported for the same amount of volume. The energy density of a fuel per unit mass is called the energy of that fuel. The greatest energy source by far is mass itself and this energy, E = mc2, where m = ρV, ρ is the mass per unit volume, V is the volume of the mass itself and c is the speed of light. This energy, however, can be released only by the processes of nuclear fission, nuclear fusion, nuclear reactions cannot be realized by chemical reactions such as combustion. Although greater matter densities can be achieved, the density of a star would approximate the most dense system capable of matter-antimatter annihilation possible. A black hole, although denser than a star, does not have an equivalent anti-particle form. In the case of small black holes the power output would be tremendous. The highest density sources of energy aside from antimatter are fusion and fission, fusion includes energy from the sun which will be available for billions of years but so far, sustained fusion power production continues to be elusive
listen)) (Non-SI unit, symbol: t), commonly referred to as the metric ton in the United States, is a non-SI metric unit of mass equal to 1,000 kilograms;[1][2][3][4] or one megagram (Mg); it is equivalent to approximately 2,204.6 pounds,[5] 1.102 short tons (US) or 0.984 long tons (imperial). Although not part of the SI, the tonne is accepted for use with SI units and prefixes by the International Committee for Weights and Measures.[6]
