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Sound Velocity
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At , the speed of sound in air is about , or one kilometre in or one mile in . It depends strongly on temperature as well as the medium through which a sound wave is propagating. At , the speed of sound in air is about . The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior. In colloquial speech, ''speed of sound'' refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: typically, sound travels most slowly in gases, faster in liquids, and fastest in solids. For example, while sound travels at in air, it travels at in water (almost 4.3 times as fast) and at in iron (almost 15 times as fast). In an exceptionally stiff material such as diamond, sound travels at , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FA-18 Hornet Breaking Sound Barrier (7 July 1999) - Filtered
The McDonnell Douglas F/A-18 Hornet is an all-weather, twinjet, twin-engine, supersonic aircraft, supersonic, carrier-based aircraft, carrier-capable, Multirole combat aircraft, multirole combat aircraft, designed as both a Fighter aircraft, fighter and attack aircraft (hence the F/A 1962 United States Tri-Service aircraft designation system, designation). Designed by McDonnell Douglas (now part of Boeing) and Northrop Corporation, Northrop (now part of Northrop Grumman), the F/A-18 was derived from the latter's YF-17 in the 1970s for use by the United States Navy and United States Marine Corps, Marine Corps. The Hornet is also used by the air forces of several other nations, and formerly by the U.S. Navy's Flight Demonstration Squadron, the Blue Angels. The F/A-18 was designed to be a highly versatile aircraft due to its avionics, cockpit displays, and excellent aerodynamic characteristics, with the ability to carry a wide variety of weapons. The aircraft can perform escort f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mach Number
Mach number (M or Ma) (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It is named after the Moravian physicist and philosopher Ernst Mach. : \mathrm = \frac, where: : is the local Mach number, : is the local flow velocity with respect to the boundaries (either internal, such as an object immersed in the flow, or external, like a channel), and : is the speed of sound in the medium, which in air varies with the square root of the thermodynamic temperature. By definition, at Mach1, the local flow velocity is equal to the speed of sound. At Mach0.65, is 65% of the speed of sound (subsonic), and, at Mach1.35, is 35% faster than the speed of sound (supersonic). Pilots of high-altitude aerospace vehicles use flight Mach number to express a vehicle's true airspeed, but the flow field around a vehicle varies in three dimensions, with corresponding variations in local Mach number. The local spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foot (unit)
The foot ( feet), standard symbol: ft, is a unit of length in the British imperial and United States customary systems of measurement. The prime symbol, , is a customarily used alternative symbol. Since the International Yard and Pound Agreement of 1959, one foot is defined as 0.3048 meters exactly. In both customary and imperial units, one foot comprises 12 inches and one yard comprises three feet. Historically the "foot" was a part of many local systems of units, including the Greek, Roman, Chinese, French, and English systems. It varied in length from country to country, from city to city, and sometimes from trade to trade. Its length was usually between 250 mm and 335 mm and was generally, but not always, subdivided into 12 inches or 16 digits. The United States is the only industrialized nation that uses the international foot and the survey foot (a customary unit of length) in preference to the meter in its commercial, engin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paris Inch
The Paris inch or pouce is an archaic unit of length that, among other uses, was common for giving the measurement of lenses. The Paris inch could be subdivided into 12 Paris lines (''ligne''), and 12 Paris inches made a Paris foot. The abbreviations are the same as for other inch and foot units, i.e: for Paris foot a unique prime symbol ( ′ ), for Paris inch a double prime symbol ( ″ ) and for Paris line a triple prime symbol ( ‴ ), The Paris inch is longer than the English inch and the Vienna inch, although the Vienna inch was subdivided with a decimal, not 12 lines. A famous measurement made using the Paris inch is the lens measurement of the first great refractor telescope, the Dorpat Great Refractor, also known as the Fraunhofer 9-inch. The 9-Paris inch diameter lens was made by Joseph von Fraunhofer, which works out to about 24.4 centimetres (9.59 English inches). This lens had the largest aperture of its day for an achromatic lens. The term for telescopes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rector (ecclesiastical)
A rector is, in an ecclesiastical sense, a cleric who functions as an administrative leader in some Christian denominations. In contrast, a vicar is also a cleric but functions as an assistant and representative of an administrative leader. Ancient usage In ancient times bishops, as rulers of cities and provinces, especially in the Papal States, were called rectors, as were administrators of the patrimony of the Church (e.g. '). The Latin term ' was used by Pope Gregory I in ''Regula Pastoralis'' as equivalent to the Latin term ' (shepherd). Roman Catholic Church In the Roman Catholic Church, a rector is a person who holds the ''office'' of presiding over an ecclesiastical institution. The institution may be a particular building—such as a church (called his rectory church) or shrine—or it may be an organization, such as a parish, a mission or quasi-parish, a seminary or house of studies, a university, a hospital, or a community of clerics or religious. If a r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Derham
William Derham FRS (26 November 16575 April 1735)Smolenaars, Marja.Derham, William (1657–1735), ''Oxford Dictionary of National Biography'', Oxford University Press, 2004. Accessed 26 May 2007. was an English clergyman, natural theologian, natural philosopher and scientist. He produced the earliest reasonably accurate measurement of the speed of sound. Life William Derham was the son of Thomas Derham. He was born at Stoulton, in Worcestershire, England. He was educated at Blockley, Gloucestershire, and at Trinity College, Oxford, from 1675 to 1679. He was ordained on 29 May 1681. In 1682, he became vicar of Wargrave, Berkshire, and from 1689 to 1735 he was Rector at Upminster, Essex. While at Upminster, in 1716 he became a Canon of Windsor and the vestry minutes show that thereafter he divided his time between those two places. The parish registers of Upminster record his burial at St. Laurence's in 1735. However, the precise site of his grave is unknown and, in accordance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Boyle
Robert Boyle (; 25 January 1627 – 31 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, alchemist and inventor. Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of modern chemistry, and one of the pioneers of modern experimental scientific method. He is best known for Boyle's law, which describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system. Among his works, '' The Sceptical Chymist'' is seen as a cornerstone book in the field of chemistry. He was a devout and pious Anglican and is noted for his writings in theology. Biography Early years Boyle was born at Lismore Castle, in County Waterford, Ireland, the seventh son and fourteenth child of The 1st Earl of Cork ('the Great Earl of Cork') and Catherine Fenton. Lord Cork, then known simply as Richard Boyle, had arrived in Dublin from England i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre Gassendi
Pierre Gassendi (; also Pierre Gassend, Petrus Gassendi; 22 January 1592 – 24 October 1655) was a French philosopher, Catholic priest, astronomer, and mathematician. While he held a church position in south-east France, he also spent much time in Paris, where he was a leader of a group of free-thinking intellectuals. He was also an active observational scientist, publishing the first data on the transit of Mercury in 1631. The lunar crater Gassendi is named after him. He wrote numerous philosophical works, and some of the positions he worked out are considered significant, finding a way between skepticism and dogmatism. Richard Popkin indicates that Gassendi was one of the first thinkers to formulate the modern "scientific outlook", of moderated skepticism and empiricism. He clashed with his contemporary Descartes on the possibility of certain knowledge. His best known intellectual project attempted to reconcile Epicurean atomism with Christianity. Biography Early life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marin Mersenne
Marin Mersenne, OM (also known as Marinus Mersennus or ''le Père'' Mersenne; ; 8 September 1588 – 1 September 1648) was a French polymath whose works touched a wide variety of fields. He is perhaps best known today among mathematicians for Mersenne prime numbers, those which can be written in the form for some integer . He also developed Mersenne's laws, which describe the harmonics of a vibrating string (such as may be found on guitars and pianos), and his seminal work on music theory, ''Harmonie universelle'', for which he is referred to as the "father of acoustics". Mersenne, an ordained Catholic priest, had many contacts in the scientific world and has been called "the center of the world of science and mathematics during the first half of the 1600s" and, because of his ability to make connections between people and ideas, "the post-box of Europe". He was also a member of the Minim religious order and wrote and lectured on theology and philosophy. Life Mersenne was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre-Simon Laplace
Pierre-Simon, marquis de Laplace (; ; 23 March 1749 – 5 March 1827) was a French scholar and polymath whose work was important to the development of engineering, mathematics, statistics, physics, astronomy, and philosophy. He summarized and extended the work of his predecessors in his five-volume ''Mécanique céleste'' (''Celestial Mechanics'') (1799–1825). This work translated the geometric study of classical mechanics to one based on calculus, opening up a broader range of problems. In statistics, the Bayesian interpretation of probability was developed mainly by Laplace. Laplace formulated Laplace's equation, and pioneered the Laplace transform which appears in many branches of mathematical physics, a field that he took a leading role in forming. The Laplacian differential operator, widely used in mathematics, is also named after him. He restated and developed the nebular hypothesis of the origin of the Solar System and was one of the first scientists to sugges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isothermal Process
In thermodynamics, an isothermal process is a type of thermodynamic process in which the temperature ''T'' of a system remains constant: Δ''T'' = 0. This typically occurs when a system is in contact with an outside thermal reservoir, and a change in the system occurs slowly enough to allow the system to be continuously adjusted to the temperature of the reservoir through heat exchange (see quasi-equilibrium). In contrast, an ''adiabatic process'' is where a system exchanges no heat with its surroundings (''Q'' = 0). Simply, we can say that in an isothermal process * T = \text * \Delta T = 0 * dT = 0 * For ideal gases only, internal energy \Delta U = 0 while in adiabatic processes: * Q = 0. Etymology The adjective "isothermal" is derived from the Greek words "ἴσος" ("isos") meaning "equal" and "θέρμη" ("therme") meaning "heat". Examples Isothermal processes can occur in any kind of system that has some means of regulating the temperature, including ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adiabatic Process
In thermodynamics, an adiabatic process (Greek: ''adiábatos'', "impassable") is a type of thermodynamic process that occurs without transferring heat or mass between the thermodynamic system and its environment. Unlike an isothermal process, an adiabatic process transfers energy to the surroundings only as work.. A translation may be founhere. Also a mostly reliabltranslation is to be foundin As a key concept in thermodynamics, the adiabatic process supports the theory that explains the first law of thermodynamics. Some chemical and physical processes occur too rapidly for energy to enter or leave the system as heat, allowing a convenient "adiabatic approximation".Bailyn, M. (1994), pp. 52–53. For example, the adiabatic flame temperature uses this approximation to calculate the upper limit of flame temperature by assuming combustion loses no heat to its surroundings. In meteorology and oceanography, adiabatic cooling produces condensation of moisture or salinity, oversatu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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