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 |
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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 ...
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 ...
Green heating and cooling technology turns carbon from eco-villain to hero
Nov 10, 2009 |
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Carbon is usually typecast as a villain in terms of the environment but researchers at the University of Warwick have devised a novel way to miniaturise a technology that will make carbon a key material in ...
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 ...
Inhibitor of Heat Shock Protein is a Potential Anticancer Drug, Study Finds
Oct 29, 2009 |
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(PhysOrg.com) -- Like yoga for office drones, cells do have coping strategies for stress. Heat, lack of nutrients, oxygen radicals - all can wreak havoc on the delicate internal components of a cell, potentially ...
A silo fire doesn't have to ruin all stored silage
Oct 27, 2009 |
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(PhysOrg.com) -- Sometimes, when harvest conditions are less than ideal, silage with lower-than-optimum moisture levels is put into a silo, potentially leading to excessive heating and a spontaneous-combustion ...
Scientists Develop New Method to Quantify Climate Modeling Uncertainty
Space & Earth / Earth Sciences
Oct 21, 2009 |
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(PhysOrg.com) -- Climate scientists recognize that climate modeling projections include a significant level of uncertainty. A team of researchers using computing facilities at Oak Ridge National Laboratory has identified ...
The future of electricity may be found in environmentally-friendly, thermoelectric cells
Oct 14, 2009 |
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The Air Force Office of Scientific Research and the National Science Foundation are funding research that may result in a military turbine aircraft that for the first time ever will produce its own electricity from exhaust ...
Hollow spheres made of metal
Oct 13, 2009 |
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Producing metallic hollow spheres is complicated: It has not yet been possible to make the small sizes required for new high-tech applications. Now for the first time researchers have manufactured ground hollow ...
Growth versus global warming
Oct 12, 2009 |
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(PhysOrg.com) -- Houses on stilts, small scale energy generation and recycling our dishwater are just some of the measures that are being proposed to prepare our cities for the effects of global warming.
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.
Energy-autonomous sensors for aircraft
Oct 01, 2009 |
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Aircraft maintenance will be easier in future, with sensors monitoring the aircraft skin. If they discover any dents or cracks they will send a radio message to a monitoring unit. The energy needed for this ...
Warming, heat waves projected to grow worse with large regional variability
Space & Earth / Earth Sciences
Sep 30, 2009 |
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(PhysOrg.com) -- While long-term projections call for higher temperatures and heat waves even more intense than previously thought, considerable geographic variability is also in the forecast, according to a study published ...
Climate talks resume in Bangkok with deal in doubt
Sep 26, 2009 |
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(AP) -- Two years ago, governments from around the world came together on the island of Bali and agreed to urgently rein in the heat-trapping gases blamed for deadly heat waves, melting glaciers and rising ...
