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.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with heat
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.
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 ...
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 ...
Turning heat to electricity... efficiently
Nov 18, 2009 |
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(PhysOrg.com) -- In everything from computer processor chips to car engines to electric powerplants, the need to get rid of excess heat creates a major source of inefficiency. But new research points the way ...
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 ...
Solar power generation around the clock
Nov 05, 2009 |
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(PhysOrg.com) -- A Californian company, SolarReserve, is developing a solar power system that can store seven hours' worth of solar energy by focusing mirrors onto millions of gallons of molten salt, allowing ...
Study: Sea stars bulk up to beat the heat
Nov 17, 2009 |
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A new study finds that a species of sea star stays cool using a strategy never before seen in the animal kingdom. The sea stars soak up cold sea water into their bodies during high tide as buffer against potentially damaging ...
Record high temperatures far outpace record lows across US (w/ Video)
Space & Earth / Earth Sciences
Nov 12, 2009 |
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Spurred by a warming climate, daily record high temperatures occurred twice as often as record lows over the last decade across the continental United States, new research shows. The ratio of record highs ...
Scientists Develop First Chip-Scale Thermoelectric Cooler
Feb 02, 2009 |
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(PhysOrg.com) -- As computer chips become more powerful, they also become hotter. Nearly all the power that flows into a chip comes out of it as waste heat, and that heat hurts the performance of the chip. ...
Scientists Propose Thermal Memory to Store Data
Jan 07, 2009 |
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Most computers today store memory electronically, by maintaining a certain voltage. In contrast, a new kind of memory that stores data thermally, by maintaining temperature, is being investigated by researchers Lei Wang of ...
Computer scientist to 'unroll' papyrus scrolls buried by Vesuvius
Technology / Computer Sciences
May 24, 2009 |
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On Aug. 24, 79 A.D., Italy's Mount Vesuvius exploded, burying the Roman towns of Herculaneum and Pompeii under tons of super-heated ash, rock and debris in one of the most famous volcanic eruptions in history.
Cosmic entropy could be 100 times greater than previously thought
Oct 06, 2009 |
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(PhysOrg.com) -- A new analysis of supermassive black holes has discovered the entropy of the universe is much greater than previously thought, which means it may also be very slightly closer to ultimate heat death.
Early modern humans use fire to engineer tools from stone
Other Sciences / Archaeology & Fossils
Aug 13, 2009 |
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(PhysOrg.com) -- Evidence that early modern humans living on the coast of the far southern tip of Africa 72,000 years ago employed pyrotechnology - the controlled use of fire - to increase the quality and ...
Breaking the Planck's law, at the nanoscale
Jul 29, 2009 |
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(PhysOrg.com) -- A well-established physical law describes the transfer of heat between two objects, but some physicists have long predicted that the law should break down when the objects are very close together. ...
Computation helps predict heat transfer in diamond
Sep 22, 2009 |
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(PhysOrg.com) -- Cornell researcher Derek Stewart and collaborators have calculated the exact mechanism by which diamond conducts heat, a breakthrough that could lend insight into many fields, including electronics.
