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Maxwell's Demon
Maxwell's demon is a thought experiment that would hypothetically violate the second law of thermodynamics. It was proposed by the physicist James Clerk Maxwell in 1867. In his first letter Maxwell called the demon a "finite being", while the ''Daemon'' name was first used by Lord Kelvin. In the thought experiment, a demon controls a small massless door between two chambers of gas. As individual gas molecules (or atoms) approach the door, the demon quickly opens and closes the door to allow only fast-moving molecules to pass through in one direction, and only slow-moving molecules to pass through in the other. Because the kinetic temperature of a gas depends on the velocities of its constituent molecules, the demon's actions cause one chamber to warm up and the other to cool down. This would decrease the total entropy of the two gases, without applying any work, thereby violating the second law of thermodynamics. The concept of Maxwell's demon has provoked substantial debate i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell's Demon
Maxwell's demon is a thought experiment that would hypothetically violate the second law of thermodynamics. It was proposed by the physicist James Clerk Maxwell in 1867. In his first letter Maxwell called the demon a "finite being", while the ''Daemon'' name was first used by Lord Kelvin. In the thought experiment, a demon controls a small massless door between two chambers of gas. As individual gas molecules (or atoms) approach the door, the demon quickly opens and closes the door to allow only fast-moving molecules to pass through in one direction, and only slow-moving molecules to pass through in the other. Because the kinetic temperature of a gas depends on the velocities of its constituent molecules, the demon's actions cause one chamber to warm up and the other to cool down. This would decrease the total entropy of the two gases, without applying any work, thereby violating the second law of thermodynamics. The concept of Maxwell's demon has provoked substantial debate i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leff Rex 02 , a premium beer brand
{{disambiguation ...
Leff may refer to: People Surname * Ari Leff, musician * Arthur Allen Leff (1935–1981), American professor of law * Barbara Leff (born 1947), American politician * Enrique Leff, a Mexican economist * Harvey S. Leff (born 1937), United States physicist * Laurel Leff, author * Michael Leff (1941–2010), U.S. scholar of rhetoric * Nathaniel Leff, American economist * Pincus Leff, comedian * Robert Leff, American businessman * Zev Leff, Israeli Rabbi Given name * Leff Pouishnoff (1891–1959), Ukrainian-born pianist and composer Other uses * Leff (river), in Brittany, France See also * Leffe Leffe () is a premium beer brand owned by InBev Belgium, the European operating arm of the global Anheuser–Busch InBev brewery giant. There are several beers in the range, and they are marketed as abbey beers. They are brewed in large quan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light. Energy is a conserved quantity—the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The unit of measurement for energy in the International System of Units (SI) is the joule (J). Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the radiant energy carried by electromagnetic radiation, and the internal energy contained within a thermodynamic system. All living organisms constantly take in and release energy. Due to mass–energy equivalence, any object that has mass whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Work (physics)
In physics, work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, for a constant force aligned with the direction of motion, the work equals the product of the force strength and the distance traveled. A force is said to do ''positive work'' if when applied it has a component in the direction of the displacement of the point of application. A force does ''negative work'' if it has a component opposite to the direction of the displacement at the point of application of the force. For example, when a ball is held above the ground and then dropped, the work done by the gravitational force on the ball as it falls is positive, and is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement). If the ball is thrown upwards, the work done by its weight is negative, and is equal to the weight multiplied by the displacement in the upwards direction. When the force is consta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Engine
In thermodynamics and engineering, a heat engine is a system that converts heat to mechanical energy, which can then be used to do mechanical work. It does this by bringing a working substance from a higher state temperature to a lower state temperature. A heat source generates thermal energy that brings the working substance to the higher temperature state. The working substance generates work in the working body of the engine while transferring heat to the colder sink until it reaches a lower temperature state. During this process some of the thermal energy is converted into work by exploiting the properties of the working substance. The working substance can be any system with a non-zero heat capacity, but it usually is a gas or liquid. During this process, some heat is normally lost to the surroundings and is not converted to work. Also, some energy is unusable because of friction and drag. In general, an engine is any machine that converts energy to mechanical work. Heat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speed
In everyday use and in kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero. Speed is not the same as velocity. Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph). For air and marine travel, the knot is commonly used. The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in a vacuum ''c'' = metres per second ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not consid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leff Rex 90 , a premium beer brand
{{disambiguation ...
Leff may refer to: People Surname * Ari Leff, musician * Arthur Allen Leff (1935–1981), American professor of law * Barbara Leff (born 1947), American politician * Enrique Leff, a Mexican economist * Harvey S. Leff (born 1937), United States physicist * Laurel Leff, author * Michael Leff (1941–2010), U.S. scholar of rhetoric * Nathaniel Leff, American economist * Pincus Leff, comedian * Robert Leff, American businessman * Zev Leff, Israeli Rabbi Given name * Leff Pouishnoff (1891–1959), Ukrainian-born pianist and composer Other uses * Leff (river), in Brittany, France See also * Leffe Leffe () is a premium beer brand owned by InBev Belgium, the European operating arm of the global Anheuser–Busch InBev brewery giant. There are several beers in the range, and they are marketed as abbey beers. They are brewed in large quan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isolated System
In physical science, an isolated system is either of the following: # a physical system so far removed from other systems that it does not interact with them. # a thermodynamic system enclosed by rigid immovable walls through which neither mass nor energy can pass. Though subject internally to its own gravity, an isolated system is usually taken to be outside the reach of external gravitational and other long-range forces. This can be contrasted with what (in the more common terminology used in thermodynamics) is called a closed system, being enclosed by selective walls through which energy can pass as heat or work, but not matter; and with an open system, which both matter and energy can enter or exit, though it may have variously impermeable walls in parts of its boundaries. An isolated system obeys the conservation law that its total energy–mass stays constant. Most often, in thermodynamics, mass and energy are treated as separately conserved. Because of the require ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called ''centigrade''), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes. The kelvin is one of the seven base units in the International System of Units (SI). Absolute zero, i.e., zero kelvin or −273.15 °C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. It would be impossible to extract energy as heat from a body at that temperature. Temperature is important in all fields of natur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Broadview Press
Broadview Press is an independent academic publisher that focuses on the humanities. Founded in 1985 by Don LePan, the company now employs over 30 people, has over 800 titles in print, and publishes approximately 40 titles each year. Broadview's offices are located across Canada in Calgary, Peterborough, Nanaimo, Guelph and Wolfville. History In its early years, Broadview operated out of LePan's home in Peterborough, Ontario, publishing a small number of titles for both Trade and academic markets. With the publication of books such as ''The Broadview Anthology of Poetry'', ''The Broadview Reader'', and the first few titles in the Broadview Editions series in the early 1990s, Broadview began to focus exclusively on the academic market. In May 2008 Broadview's social science and history lists were sold to the University of Toronto Press. Michael Harrison (Broadview Vice-President 1992-2004, and President 2005-2008) and several staff members went on to form the Higher Education divis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daimon
Daimon or Daemon (Ancient Greek: , "god", "godlike", "power", "fate") originally referred to a lesser deity or guiding spirit such as the daimons of ancient Greek religion and mythology and of later Hellenistic religion and philosophy. The word is derived from Proto-Indo-European ''daimon'' "provider, divider (of fortunes or destinies)," from the root ''*da-'' "to divide". Daimons were possibly seen as the souls of men of the golden age acting as tutelary deities, according to entry at Liddell & Scott. See also daimonic: a religious, philosophical, literary and psychological concept. Description Daimons are lesser divinities or spirits, often personifications of abstract concepts, beings of the same nature as both mortals and deities, similar to ghosts, chthonic heroes, spirit guides, forces of nature, or the deities themselves (see Plato's ''Symposium''). According to Hesiod's myth, "great and powerful figures were to be honoured after death as a daimon…" A daimon is not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
