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
Turning heat to electricity... efficiently
Nov 18, 2009 |
4.8 / 5 (65) |
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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 ...
Material may help autos turn heat into electricity
Nanotechnology / Nanomaterials
Jul 24, 2008 |
4.4 / 5 (64) |
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Researchers have invented a new material that will make cars even more efficient, by converting heat wasted through engine exhaust into electricity. In the current issue of the journal Science, they describe a material with t ...
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 ...
U.S. Crop Yields Could Wilt in Heat
Aug 24, 2009 |
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(PhysOrg.com) -- Yields of three of the most important crops produced in the United States - corn, soybeans and cotton - are predicted to fall off a cliff if temperatures rise due to climate change.
Deadly heat waves are becoming more frequent in California
Space & Earth / Earth Sciences
Aug 25, 2009 |
4.8 / 5 (50) |
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From mid July to early August 2006, a heat wave swept through the southwestern United States. Temperature records were broken at many locations and unusually high humidity levels for this typically arid region ...
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 ...
Alternative energy hits the road
Aug 12, 2008 |
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Anyone who has walked barefoot across a parking lot on a hot summer day knows that blacktop is exceptionally good at soaking up the sun's warmth. Now, a research team at Worcester Polytechnic Institute (WPI) has found a way ...
New nano technique significantly boosts boiling efficiency
Jun 26, 2008 |
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Whoever penned the old adage "a watched pot never boils" surely never tried to heat up water in a pot lined with copper nanorods.
Congress considers major global warming measure
Apr 19, 2009 |
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(AP) -- The last time Congress passed major environmental laws, acid rain was destroying lakes and forests, polluted rivers were on fire and smog was choking people in some cities.
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 ...
Breaking the Planck's law, at the nanoscale
Jul 29, 2009 |
5 / 5 (25) |
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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. ...
'Nanosculpture' could enable new types of heat pumps, energy converters
Nanotechnology / Nanomaterials
Jul 17, 2008 |
4.6 / 5 (25) |
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A new technique for growing single-crystal nanorods and controlling their shape using biomolecules could enable the development of smaller, more powerful heat pumps and devices that harvest electricity from ...
Nanoparticle Research Points to Energy Savings
Nanotechnology / Nanomaterials
Jul 23, 2008 |
4.9 / 5 (23) |
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(PhysOrg.com) -- Adding just the right dash of nanoparticles to standard mixes of lubricants and refrigerants could yield the equivalent of an energy-saving chill pill for factories, hospitals, ships, and ...
Electronic heat trap grips deep Earth
Space & Earth / Earth Sciences
Nov 12, 2008 |
4.1 / 5 (27) |
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(PhysOrg.com) -- The key to understanding Earth's evolution, including how our atmosphere gained oxygen and how volcanoes and earthquakes form, is to look deep, really deep, into the lower mantle—a region ...
Plate tectonics started over 4 billion years ago, geochemists report
Space & Earth / Earth Sciences
Nov 26, 2008 |
4.6 / 5 (23) |
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(PhysOrg.com) -- A new picture of the early Earth is emerging, including the surprising finding that plate tectonics may have started more than 4 billion years ago — much earlier than scientists had believed, ...
