Question #b9216

1 Answer
Mar 26, 2015

Well, "heat" as such is not a precise scientific term; one ususally says "heat energy". In that case it usually refers to the energy that can be passed from one body to another owing to a temperature difference.
On the other hand, "temperature" is a measure of "how hot" a body is and is indeed related to the heat energy it contains. However, for a given temperature the amount of heat energy a given body contains varies from body to body (or substance to substance).

Indeed, we talk of the "heat capacity" of substances: different substances need different amounts of energy to raise their temperatures by, say, one degree.

Heat energy at the microscopic level is just the kinetic energy of the atoms ot molecules of which a substance is composed. The point then is that the total kinetic energy is the sum of translational (i.e. just the usual #1/2 mv^2#), rotational and vibrational energies. These last come into play at different temperatures (in different substances and may in some case not be presnt at all) so that heat capacity actually even varies with temperature.