What term describes the transfer of kinetic energy from one substance to another?

The term that describes the transfer of kinetic energy from one substance to another is heat. In thermodynamics, heat refers specifically to the energy that is transferred between systems or bodies due to a temperature difference. When two substances at different temperatures come into contact, the kinetic energy of the particles will move from the hotter substance (with higher kinetic energy) to the colder substance (with lower kinetic energy) until thermal equilibrium is reached. This process is often observed in everyday life, such as when a warm object heats up a cooler one.

Temperature, while related to the concept of thermal energy, specifically measures the average kinetic energy of the particles in a substance, rather than the transfer of energy itself. Kinetic energy refers to the energy that an object possesses because of its motion, but it does not encompass the transfer aspect that is central to the definition of heat. Caloric theory, an outdated scientific theory, was once used to explain heat transfer but has since been replaced by modern thermodynamics, which more accurately describes heat in terms of energy transfer. Therefore, heat is the most accurate term for the transfer of kinetic energy from one substance to another.