This question already has an answer here:

I learned that the average kinetic energy has $$ E_k = \frac{3}{2}\ kT. $$ But if heat is in essence molecular motion, then is a rapidly moving ball different with a still one?


marked as duplicate by John Rennie energy Apr 6 at 5:40

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.