Heat
hideIn physics and thermodynamics, heat is the process of energy transfer from one body or system to another due to a difference in temperature. In thermodynamics, the quantity TdS is used as a representative measure of the (inexact) heat differential δQ, which is the absolute temperature of an object multiplied by the differential quantity of a system's entropy measured at the boundary of the object.
A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature. Heat is also loosely referred to as thermal energy, although many definitions require this thermal energy to actually be in the process of movement between one body and another to be technically called heat (otherwise, many sources prefer to continue to refer to the static quantity as "thermal energy"). Heat is also known as "Energy".
Energy transfer by heat can occur between objects by radiation, conduction and convection. Temperature is used as a measure of the internal energy or enthalpy, that is the level of elementary motion giving rise to heat transfer. Energy can only be transferred by heat between objects - or areas within an object - with different temperatures (as given by the zeroth law of thermodynamics). This transfer happens spontaneously only in the direction of the colder body (as per the second law of thermodynamics). The transfer of energy by heat from one object to another object with an equal or higher temperature can happen only with the aid of a heat pump, which does work.
For more information about Heat, read the full article at
Wikipedia.
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News tagged with heat
Scientists Create Material More Insulating than the Vacuum
Dec 10, 2009 |
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(PhysOrg.com) -- With its complete lack of atoms, a vacuum is often considered to be the best known insulator. For this reason, vacuums are regularly used to reduce heat transfer, such as in the lining of ...
Superconductor magnet spacecraft heat shield being developed
Nov 26, 2009 |
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(PhysOrg.com) -- European space agencies and an aerospace giant are developing a new re-entry heat shield that will use superconductor magnets to generate a magnetic field strong enough to deflect the superhot ...
Physicists lay the groundwork for cooler, faster computing
Dec 14, 2009 |
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University of Toronto quantum optics researchers Sajeev John and Xun Ma have discovered new behaviours of light within photonic crystals that could lead to faster optical information processing and compact computers that ...
Researcher Uses Graphene Quilts to Keep Things Cool
Nanotechnology / Nanomaterials
Dec 21, 2009 |
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(PhysOrg.com) -- University of California, Riverside Professor of Electrical Engineering and Chair of Materials Science and Engineering Alexander Balandin is leading several projects to explore ways to use ...
New materials designed to deal with hypersonic and supersonic hot stuff (w/ Video)
Dec 24, 2009 |
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University of Queensland researchers are testing new materials to withstand the extreme heat experienced by hypersonic vehicles in flight so they can fly for substantially longer.
Turbulence around heat transport
Dec 03, 2009 |
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(PhysOrg.com) -- Heat transport in the earth's mantle and in the atmosphere is probably not as effective as previously thought.
Disproportionate effects of global warming and pollution on disadvantaged communities
Dec 22, 2009 |
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Global warming, pollution, and the environmental consequences of energy production impose a greater burden on low-income, disadvantaged communities, and strategies to prevent these inequities are urgently needed. A provocative ...
Fujitsu Announces World's First Operation of 100W-Class Amplifiers Employing Carbon Nanotubes
Dec 11, 2009 |
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Fujitsu Laboratories today announced that, using carbon nanotubes as heat-dissipation material in amplifier transistors, Fujitsu has become the first to achieve the successful operation of high-frequency, ...
First metallic nanoparticles resistant to extreme heat
Nanotechnology / Nanomaterials
Nov 30, 2009 |
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A University of Pittsburgh team overcame a major hurdle plaguing the development of nanomaterials such as those that could lead to more efficient catalysts used to produce hydrogen and render car exhaust less toxic. The researchers ...
Researchers look at water-energy impacts of climate change
Dec 01, 2009 |
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(PhysOrg.com) -- Climate projections for the next 50 to 100 years forecast increasingly frequent severe droughts and heat waves across the American Southwest, sinking available water levels even as rising mercury drives up ...
Ecosystem, vegetation affect intensity of urban heat island effect
Space & Earth / Earth Sciences
Dec 15, 2009 |
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NASA researchers studying urban landscapes have found that the intensity of the "heat island" created by a city depends on the ecosystem it replaced and on the regional climate. Urban areas developed in arid and semi-arid ...
Panasonic Starts Mass-Production of High-Capacity 3.1 Ah Lithium-ion Battery
Dec 18, 2009 |
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Panasonic Corporation developed a 18650-type high-capacity 3.1 Ah lithium-ion battery and began mass production of the battery this December. The new 3.1 Ah battery has a nickel positive electrode and an energy density of ...
