Thermal Energy

Thermal energy — the energy of motion

Every atom and molecule in a substance is in constant motion, and thermal energy is simply the energy a body possesses because of that motion. It is directly proportional to the substance's temperature — the hotter the substance, the more thermal energy its particles carry.

In practice, thermal energy is the measure of the average kinetic energy of the particles making up the matter. It is this energy that keeps particles moving — this restless, temperature-driven movement of particles is called thermal motion. …