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Speed Of Sound
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elasticity (solid mechanics), elastic medium. More simply, the speed of sound is how fast vibrations travel. At , the speed of sound in air is about , or 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 dry air (sea level 14.7 psi) 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 dry air, deviating slightly from ideal behavior. In colloquial speech, ''speed of sound'' refers to the speed of sound waves in Earth's atmosphere, 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 a ... [...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 supersonic, twinjet, twin-engine, 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 and Northrop Corporation, Northrop, 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, glass cockpit, cockpit displays, and excellent aerodynamic characteristics, with the ability to carry a wide variety of weapons. The aircraft can perform escort fighter, fighter escort, fleet air defense, suppression of en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mach Number
The Mach number (M or Ma), often only Mach, (; ) 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 Austrian 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). The local speed of sound, and hence the Mach number, depends on the temperature of the surrounding gas. The Mach number is primarily used to determine the approximation with which a flow can be treated as an i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foot (unit)
The foot (standard symbol: ft) is a Units of measurement, unit of length in the imperial units, British imperial and United States customary units, United States customary systems of metrology, measurement. The prime (symbol), prime symbol, , is commonly used to represent the foot. In both customary and imperial units, one foot comprises 12 inches, and one yard comprises three feet. Since international yard and pound, an international agreement in 1959, the foot is defined as equal to exactly 0.3048 meters. Historically, the "foot" was a part of many local systems of units, including the Ancient Greek units of measurement, Greek, Ancient Roman units of measurement, Roman, Chinese units of measurement, Chinese, Units of measurement in France before the French Revolution, French, and English units, 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 ... [...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 single 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 telesco ... [...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. ... [...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 accord ... [...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, Alchemy, 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 works in theology. Biography Early years Boyle was born at Lismore Castle in County Waterford, in the far south of Ireland, the seventh son and fourteenth child of Richard Boyle, 1st Earl of Cork, the 1st Earl of Cork ("the Great Earl of Cork") and Catherine Fenton Boyle, Catherine Fenton. Lord Cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre Gassendi
Pierre Gassendi (; also Pierre Gassend, Petrus Gassendi, Petrus Gassendus; 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. ... [...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 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 ascetical Minim religious order and wrote and lectured on theology and philosophy. Life Mersenne was b ... [...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 polymath, a scholar whose work has been instrumental in the fields of physics, astronomy, mathematics, engineering, statistics, and philosophy. He summarized and extended the work of his predecessors in his five-volume Traité de mécanique céleste, ''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. Laplace also popularized and further confirmed Isaac Newton, Sir Isaac Newton's work. In statistics, the Bayesian probability, 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 Laplace operator, Laplacian differential operator, widely used in mathematic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isothermal Process
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 noun '' isotherm'' is derived from the Ancient Greek words (), meaning "equal", and (), meaning "heat". Examples Isothermal processes can occur in any kind of system that has some means of regulating the temperature, including highly structured machines, and even living ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adiabatic Process
An adiabatic process (''adiabatic'' ) is a type of thermodynamic process that occurs without transferring heat between the thermodynamic system and its Environment (systems), environment. Unlike an isothermal process, an adiabatic process transfers energy to the surroundings only as Work (thermodynamics), work and/or mass flow.. 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. The opposite term to "adiabatic" is ''diabatic''. 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 fire, flame temperature by assuming combustion loses no heat to its surroundings. In meteorology, adiabatic expansion an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
