1.
Fork
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A fork, in cutlery or kitchenware, is a tool consisting of a handle with several narrow tines on one end. The usually metal utensil is used to food to the mouth or to hold ingredients in place while they are being cut by a knife. Food can be lifted either by spearing it on the tines or by holding it on top of the tines, the early history of the fork is obscure. As a kitchen and dining utensil it is believed to have originated in the Roman Empire. The personal table fork most likely originated in the Eastern Roman Empire and its use spread to what is now the Middle East during the first millennium AD and then spread into southern Europe during the second millennium. It did not become common in northern Europe until the 18th century and was not common in North America until the 19th century, the fork is a primarily Western utensil, whereas in east Asia chopsticks have been more prevalent. Today, forks are available throughout east Asia. The word fork comes from the Latin furca, meaning pitchfork, some of the earliest known uses of forks with food occurred in Ancient Egypt, where large forks were used as cooking utensils. Bone forks had been found in the site of the Bronze Age Qijia culture as well as later Chinese dynasties tombs. The Ancient Greeks used the fork as a serving utensil, the Greek name for fork is still used in some European languages, for instance in the Venetian, Greek, and Albanian languages. In the Roman Empire, bronze and silver forks were used, the use varied according to local customs, social class and the nature of food, but forks of the earlier periods were mostly used as cooking and serving utensils. The personal table fork was most likely invented in the Eastern Roman Empire, records show that by the 9th century a similar utensil known as a barjyn was in limited use in Persia within some elite circles. By the 10th century, the fork was in common use throughout the Middle East. By the 11th century, the fork had become increasingly prevalent in the Italian peninsula. At first, pasta was consumed using a wooden spike. In Italy, it became commonplace by the 14th century and was almost universally used by the merchant and upper classes by 1600. It was proper for a guest to arrive with his own fork and spoon enclosed in a box called a cadena, in Portugal, forks were first used at the time of Infanta Beatrice, Duchess of Viseu, King Manuel I of Portugals mother around 1450. However, forks were not commonly used in Southern Europe until the 16th century when they part of Italian etiquette
2.
Steel
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Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost. Steels base metal is iron, which is able to take on two forms, body centered cubic and face centered cubic, depending on its temperature. It is the interaction of those allotropes with the elements, primarily carbon. In the body-centred cubic arrangement, there is an atom in the centre of each cube. Carbon, other elements, and inclusions within iron act as hardening agents that prevent the movement of dislocations that otherwise occur in the lattices of iron atoms. The carbon in steel alloys may contribute up to 2. 1% of its weight. Steels strength compared to pure iron is possible at the expense of irons ductility. With the invention of the Bessemer process in the mid-19th century and this was followed by Siemens-Martin process and then Gilchrist-Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron, further refinements in the process, such as basic oxygen steelmaking, largely replaced earlier methods by further lowering the cost of production and increasing the quality of the product. Today, steel is one of the most common materials in the world and it is a major component in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations, the noun steel originates from the Proto-Germanic adjective stakhlijan, which is related to stakhla. The carbon content of steel is between 0. 002% and 2. 1% by weight for plain iron–carbon alloys and these values vary depending on alloying elements such as manganese, chromium, nickel, iron, tungsten, carbon and so on. Basically, steel is an alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction, too little carbon content leaves iron quite soft, ductile, and weak. Carbon contents higher than those of steel make an alloy, commonly called pig iron, while iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include, manganese, nickel, chromium, molybdenum, boron, titanium, vanadium, tungsten, cobalt, and niobium. Additional elements are important in steel, phosphorus, sulfur, silicon, and traces of oxygen, nitrogen, and copper. Alloys with a higher than 2. 1% carbon content, depending on other element content, cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties
3.
Trumpet
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A trumpet is a musical instrument commonly used in classical and jazz ensembles. The trumpet group contains the instruments with the highest register in the brass family, trumpets are used in art music styles, for instance in orchestras, concert bands, and jazz ensembles, as well as in popular music. They are played by blowing air through almost-closed lips, producing a sound that starts a standing wave vibration in the air column inside the instrument. Since the late 15th century they have primarily been constructed of brass tubing, there are many distinct types of trumpet, with the most common being pitched in B♭, having a tubing length of about 1.48 m. Early trumpets did not provide means to change the length of tubing, most trumpets have valves of the piston type, while some have the rotary type. The use of rotary-valved trumpets is more common in orchestral settings, each valve, when engaged, increases the length of tubing, lowering the pitch of the instrument. A musician who plays the trumpet is called a trumpet player or trumpeter, the earliest trumpets date back to 1500 BC and earlier. The bronze and silver trumpets from Tutankhamuns grave in Egypt, bronze lurs from Scandinavia, trumpets from the Oxus civilization of Central Asia have decorated swellings in the middle, yet are made out of one sheet of metal, which is considered a technical wonder. The Shofar, made from a ram horn and the Hatzotzeroth and they were played in Solomons Temple around 3000 years ago. They were said to be used to blow down the walls of Jericho and they are still used on certain religious days. The Salpinx was a straight trumpet 62 inches long, made of bone or bronze, Salpinx contests were a part of the original Olympic Games. The Moche people of ancient Peru depicted trumpets in their art going back to AD300, the earliest trumpets were signaling instruments used for military or religious purposes, rather than music in the modern sense, and the modern bugle continues this signaling tradition. Improvements to instrument design and metal making in the late Middle Ages, the natural trumpets of this era consisted of a single coiled tube without valves and therefore could only produce the notes of a single overtone series. Changing keys required the player to change crooks of the instrument, the development of the upper, clarino register by specialist trumpeters—notably Cesare Bendinelli—would lend itself well to the Baroque era, also known as the Golden Age of the natural trumpet. During this period, a vast body of music was written for virtuoso trumpeters, the art was revived in the mid-20th century and natural trumpet playing is again a thriving art around the world. The melody-dominated homophony of the classical and romantic periods relegated the trumpet to a role by most major composers owing to the limitations of the natural trumpet. Berlioz wrote in 1844, Notwithstanding the real loftiness and distinguished nature of its quality of tone, there are few instruments that have been more degraded. The attempt to give the trumpet more chromatic freedom in its range saw the development of the keyed trumpet, the symphonies of Mozart, Beethoven, and as late as Brahms, were still played on natural trumpets
4.
Lute
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The European lute and the modern Near-Eastern oud descend from a common ancestor via diverging evolutionary paths. The lute is used in a variety of instrumental music from the Medieval to the late Baroque eras and was the most important instrument for secular music in the Renaissance. It is also an instrument, especially in vocal works. The player of a lute is called a lutenist, lutanist or lutist, the words lute and oud possibly derive from Arabic al-ʿud. Recent research by Eckhard Neubauer suggests ʿud may in turn be an Arabized version of the Persian name rud and it has equally been suggested the wood in the name may have distinguished the instrument by its wooden soundboard from skin-faced predecessors. Gianfranco Lotti suggests the wood appellation originally carried derogatory connotations because of proscriptions of all music in early Islam. Lutes are made almost entirely of wood, the soundboard is a teardrop-shaped thin flat plate of resonant wood. In all lutes the soundboard has a single decorated sound hole under the strings called the rose. The sound hole is not open, but rather covered with a grille in the form of a vine or a decorative knot. Robert Lundberg, in his book Historical Lute Construction, suggests ancient builders placed bars according to ratios of the scale length. He further suggests the inward bend of the soundboard is an adaptation by ancient builders to afford the lutenists right hand more space between the strings and soundboard. Soundboard thickness varies, but generally hovers between 1.5 and 2 mm, some luthiers tune the belly as they build, removing mass and adapting bracing to produce desirable sonic results. The lute belly is almost never finished, but in cases the luthier may size the top with a very thin coat of shellac or glair to help keep it clean. After joining the top to the sides, a half-binding is usually installed around the edge of the soundboard, the half-binding is approximately half the thickness of the soundboard and is usually made of a contrasting color wood. The rebate for the half-binding must be precise to avoid compromising structural integrity. The back or the shell is assembled from strips of hardwood called ribs. There are braces inside on the soundboard to give it strength, the neck is made of light wood, with a veneer of hardwood to provide durability for the fretboard beneath the strings. Unlike most modern stringed instruments, the fretboard is mounted flush with the top
5.
Interference (wave propagation)
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In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude. Interference effects can be observed with all types of waves, for example, light, radio, acoustic, surface water waves or matter waves. If a crest of a wave meets a crest of wave of the same frequency at the same point. If a crest of one wave meets a trough of another wave, constructive interference occurs when the phase difference between the waves is an even multiple of π, whereas destructive interference occurs when the difference is an odd multiple of π. If the difference between the phases is intermediate between two extremes, then the magnitude of the displacement of the summed waves lies between the minimum and maximum values. Consider, for example, what happens when two identical stones are dropped into a pool of water at different locations. Each stone generates a circular wave propagating outwards from the point where the stone was dropped, when the two waves overlap, the net displacement at a particular point is the sum of the displacements of the individual waves. At some points, these will be in phase, and will produce a maximum displacement, in other places, the waves will be in anti-phase, and there will be no net displacement at these points. Thus, parts of the surface will be stationary—these are seen in the figure above, prime examples of light interference are the famous Double-slit experiment, laser speckle, optical thin layers and films and interferometers. Dark areas in the slit are not available to the photons. Thin films also behave in a quantum manner, the above can be demonstrated in one dimension by deriving the formula for the sum of two waves. Suppose a second wave of the frequency and amplitude but with a different phase is also traveling to the right W2 = A cos where ϕ is the phase difference between the waves in radians. Constructive interference, If the phase difference is a multiple of pi. Interference is essentially a redistribution process. The energy which is lost at the interference is regained at the constructive interference. One wave is travelling horizontally, and the other is travelling downwards at an angle θ to the first wave, assuming that the two waves are in phase at the point B, then the relative phase changes along the x-axis. Constructive interference occurs when the waves are in phase, and destructive interference when they are half a cycle out of phase. Thus, a fringe pattern is produced, where the separation of the maxima is d f = λ sin θ
6.
Sheffield
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Sheffield is a city and metropolitan borough in South Yorkshire, England. Historically part of the West Riding of Yorkshire, its derives from the River Sheaf. With some of its southern suburbs annexed from Derbyshire, the city has grown from its industrial roots to encompass a wider economic base. The population of the City of Sheffield is 569,700, Sheffield is the third largest English district by population. The metropolitan population of Sheffield is 1,569,000, in the 19th century, Sheffield gained an international reputation for steel production. Known as the Steel City, many innovations were developed locally, including crucible and stainless steel, Sheffield received its municipal charter in 1843, becoming the City of Sheffield in 1893. International competition in iron and steel caused a decline in these industries in the 1970s and 1980s, the 21st century has seen extensive redevelopment in Sheffield along with other British cities. Sheffields gross value added has increased by 60% since 1997, standing at £9.2 billion in 2007, the economy has experienced steady growth averaging around 5% annually, greater than that of the broader region of Yorkshire and the Humber. The city is in the foothills of the Pennines, and the valleys of the River Don and its four tributaries, the Loxley, the Porter Brook, the Rivelin. 61% of Sheffields entire area is space, and a third of the city lies within the Peak District national park. The area now occupied by the City of Sheffield is believed to have inhabited since at least the late Upper Palaeolithic period. The earliest evidence of occupation in the Sheffield area was found at Creswell Crags to the east of the city. In the Iron Age the area became the southernmost territory of the Pennine tribe called the Brigantes and it is this tribe who are thought to have constructed several hill forts in and around Sheffield. Gradually, Anglian settlers pushed west from the kingdom of Deira, a Celtic presence within the Sheffield area is evidenced by two settlements called Wales and Waleswood close to Sheffield. The settlements that grew and merged to form Sheffield, however, date from the half of the first millennium. In Anglo-Saxon times, the Sheffield area straddled the border between the kingdoms of Mercia and Northumbria, after the Norman conquest, Sheffield Castle was built to protect the local settlements, and a small town developed that is the nucleus of the modern city. By 1296, a market had been established at what is now known as Castle Square, from 1570 to 1584, Mary, Queen of Scots, was imprisoned in Sheffield Castle and Sheffield Manor. During the 1740s, a form of the steel process was discovered that allowed the manufacture of a better quality of steel than had previously been possible
7.
England
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England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west, the Irish Sea lies northwest of England and the Celtic Sea lies to the southwest. England is separated from continental Europe by the North Sea to the east, the country covers five-eighths of the island of Great Britain in its centre and south, and includes over 100 smaller islands such as the Isles of Scilly, and the Isle of Wight. England became a state in the 10th century, and since the Age of Discovery. The Industrial Revolution began in 18th-century England, transforming its society into the worlds first industrialised nation, Englands terrain mostly comprises low hills and plains, especially in central and southern England. However, there are uplands in the north and in the southwest, the capital is London, which is the largest metropolitan area in both the United Kingdom and the European Union. In 1801, Great Britain was united with the Kingdom of Ireland through another Act of Union to become the United Kingdom of Great Britain and Ireland. In 1922 the Irish Free State seceded from the United Kingdom, leading to the latter being renamed the United Kingdom of Great Britain, the name England is derived from the Old English name Englaland, which means land of the Angles. The Angles were one of the Germanic tribes that settled in Great Britain during the Early Middle Ages, the Angles came from the Angeln peninsula in the Bay of Kiel area of the Baltic Sea. The earliest recorded use of the term, as Engla londe, is in the ninth century translation into Old English of Bedes Ecclesiastical History of the English People. According to the Oxford English Dictionary, its spelling was first used in 1538. The earliest attested reference to the Angles occurs in the 1st-century work by Tacitus, Germania, the etymology of the tribal name itself is disputed by scholars, it has been suggested that it derives from the shape of the Angeln peninsula, an angular shape. An alternative name for England is Albion, the name Albion originally referred to the entire island of Great Britain. The nominally earliest record of the name appears in the Aristotelian Corpus, specifically the 4th century BC De Mundo, in it are two very large islands called Britannia, these are Albion and Ierne. But modern scholarly consensus ascribes De Mundo not to Aristotle but to Pseudo-Aristotle, the word Albion or insula Albionum has two possible origins. Albion is now applied to England in a poetic capacity. Another romantic name for England is Loegria, related to the Welsh word for England, Lloegr, the earliest known evidence of human presence in the area now known as England was that of Homo antecessor, dating to approximately 780,000 years ago. The oldest proto-human bones discovered in England date from 500,000 years ago, Modern humans are known to have inhabited the area during the Upper Paleolithic period, though permanent settlements were only established within the last 6,000 years
8.
Trigonometric functions
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In planar geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle. Angles formed by two rays lie in a plane, but this plane does not have to be a Euclidean plane, Angles are also formed by the intersection of two planes in Euclidean and other spaces. Angles formed by the intersection of two curves in a plane are defined as the angle determined by the tangent rays at the point of intersection. Similar statements hold in space, for example, the angle formed by two great circles on a sphere is the dihedral angle between the planes determined by the great circles. Angle is also used to designate the measure of an angle or of a rotation and this measure is the ratio of the length of a circular arc to its radius. In the case of an angle, the arc is centered at the vertex. In the case of a rotation, the arc is centered at the center of the rotation and delimited by any other point and its image by the rotation. The word angle comes from the Latin word angulus, meaning corner, cognate words are the Greek ἀγκύλος, meaning crooked, curved, both are connected with the Proto-Indo-European root *ank-, meaning to bend or bow. Euclid defines a plane angle as the inclination to each other, in a plane, according to Proclus an angle must be either a quality or a quantity, or a relationship. In mathematical expressions, it is common to use Greek letters to serve as variables standing for the size of some angle, lower case Roman letters are also used, as are upper case Roman letters in the context of polygons. See the figures in this article for examples, in geometric figures, angles may also be identified by the labels attached to the three points that define them. For example, the angle at vertex A enclosed by the rays AB, sometimes, where there is no risk of confusion, the angle may be referred to simply by its vertex. However, in geometrical situations it is obvious from context that the positive angle less than or equal to 180 degrees is meant. Otherwise, a convention may be adopted so that ∠BAC always refers to the angle from B to C. Angles smaller than an angle are called acute angles. An angle equal to 1/4 turn is called a right angle, two lines that form a right angle are said to be normal, orthogonal, or perpendicular. Angles larger than an angle and smaller than a straight angle are called obtuse angles. An angle equal to 1/2 turn is called a straight angle, Angles larger than a straight angle but less than 1 turn are called reflex angles
9.
Hyperbolic function
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In mathematics, hyperbolic functions are analogs of the ordinary trigonometric, or circular functions. The inverse hyperbolic functions are the hyperbolic sine arsinh and so on. Just as the form a circle with a unit radius. The hyperbolic functions take a real argument called a hyperbolic angle, the size of a hyperbolic angle is twice the area of its hyperbolic sector. The hyperbolic functions may be defined in terms of the legs of a triangle covering this sector. Laplaces equations are important in areas of physics, including electromagnetic theory, heat transfer, fluid dynamics. In complex analysis, the hyperbolic functions arise as the parts of sine and cosine. When considered defined by a variable, the hyperbolic functions are rational functions of exponentials. Hyperbolic functions were introduced in the 1760s independently by Vincenzo Riccati, Riccati used Sc. and Cc. to refer to circular functions and Sh. and Ch. to refer to hyperbolic functions. Lambert adopted the names but altered the abbreviations to what they are today, the abbreviations sh and ch are still used in some other languages, like French and Russian. The hyperbolic functions are, Hyperbolic sine, sinh x = e x − e − x 2 = e 2 x −12 e x =1 − e −2 x 2 e − x. Hyperbolic cosine, cosh x = e x + e − x 2 = e 2 x +12 e x =1 + e −2 x 2 e − x, the complex forms in the definitions above derive from Eulers formula. One also has sech 2 x =1 − tanh 2 x csch 2 x = coth 2 x −1 for the other functions, sinh = sinh 2 = sgn cosh −12 where sgn is the sign function. All functions with this property are linear combinations of sinh and cosh, in particular the exponential functions e x and e − x, and it is possible to express the above functions as Taylor series, sinh x = x + x 33. + ⋯ = ∑ n =0 ∞ x 2 n +1, the function sinh x has a Taylor series expression with only odd exponents for x. Thus it is an odd function, that is, −sinh x = sinh, the function cosh x has a Taylor series expression with only even exponents for x. Thus it is a function, that is, symmetric with respect to the y-axis. The sum of the sinh and cosh series is the series expression of the exponential function
10.
Metre
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The metre or meter, is the base unit of length in the International System of Units. The metre is defined as the length of the path travelled by light in a vacuum in 1/299792458 seconds, the metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole. In 1799, it was redefined in terms of a metre bar. In 1960, the metre was redefined in terms of a number of wavelengths of a certain emission line of krypton-86. In 1983, the current definition was adopted, the imperial inch is defined as 0.0254 metres. One metre is about 3 3⁄8 inches longer than a yard, Metre is the standard spelling of the metric unit for length in nearly all English-speaking nations except the United States and the Philippines, which use meter. Measuring devices are spelled -meter in all variants of English, the suffix -meter has the same Greek origin as the unit of length. This range of uses is found in Latin, French, English. Thus calls for measurement and moderation. In 1668 the English cleric and philosopher John Wilkins proposed in an essay a decimal-based unit of length, as a result of the French Revolution, the French Academy of Sciences charged a commission with determining a single scale for all measures. In 1668, Wilkins proposed using Christopher Wrens suggestion of defining the metre using a pendulum with a length which produced a half-period of one second, christiaan Huygens had observed that length to be 38 Rijnland inches or 39.26 English inches. This is the equivalent of what is now known to be 997 mm, no official action was taken regarding this suggestion. In the 18th century, there were two approaches to the definition of the unit of length. One favoured Wilkins approach, to define the metre in terms of the length of a pendulum which produced a half-period of one second. The other approach was to define the metre as one ten-millionth of the length of a quadrant along the Earths meridian, that is, the distance from the Equator to the North Pole. This means that the quadrant would have defined as exactly 10000000 metres at that time. To establish a universally accepted foundation for the definition of the metre, more measurements of this meridian were needed. This portion of the meridian, assumed to be the length as the Paris meridian, was to serve as the basis for the length of the half meridian connecting the North Pole with the Equator
. PMID 3323515.
"Tuning Fork". Collier's New Encyclopedia. 1921.
