# Q & A: thermal energy

Q:
does the temperature of an object affect the object's potential and/or kinetic energy?
- alyssa
usa
A:
Increasing temperature (T) always increases total energy. For temperatures high enough to be described by classical forms of energy, each potential mode and each kinetic mode gets more energy on the average as T goes up. I can't think of any case where either the potential or the kinetic energy decreases as T is raised, but I also can't right away think of a theorem to prove that couldn't happen for some unusual system.

Mike W.

Update: With a little effort, I've come up with a somewhat peculiar example in which kinetic energy goes down as something gets hotter, over some range of T. Total energy still goes up, as it must. So although in almost any realistic case, kinetic energy goes up as T increases, there's no theorem requiring that in all cases.

further Update: Just to be clear, you can also invent strange examples in which increasing T increases kinetic energy and decreases potential energy by a smaller amount.

(published on 05/16/2013)