Thermal energy transferred from a warm body to a cooler body by virtue of their temperature difference. Heat is measured in calories. One calorie is the amount of heat necessary to rais the temperature of one gram of water by one degree Celcius. (In the British system, the unit of heat is teh BTU, whis is the amount od heat necessary to raise the temperature of one pound of water by one degree Fahrenheit.) One calorie is equal to 4.186 Joules.
