Measures of Heat Temperature is a measure of the average
translational kinetic energy of the molecules of a system. Heat
is commonly expressed in either of two units: the calorie, an
older metric unit, and the British thermal unit (Btu), an
English unit commonly used in the United States. Scientists
express heat in terms of the joule, a unit used for all forms of
energy.Specific Heat As heat is added to a substance in the
solid state, the molecules of the substance gain kinetic energy
and the temperature of the substance rises. The amount of heat
needed to raise a unit of mass of the substance one degree of
temperature is called the specific heat of the substance.
Because of the way in which the calorie and the Btu are defined,
the specific heat of any substance is the same in either system
of measurement. For example, the specific heat of water is 1
calorie per gram per degree Celsius; i.e., 1 calorie of heat is
needed to raise the temperature of 1 gram of water by 1 degree
Celsius; it is also 1 Btu per poun