Question

When you place two substances at different temperatures together, when does heat stop transferring?

a
heat transfers from the hotter object to the cooler object until they reach the same temperature
b
heat never stops transferring between objects
c
heat transfers from the cooler object to the hotter object until they reach the same temperature

Answer 1

a

Heat flows spontaneously from the hotter object to the cooler one until thermal equilibrium (the same temperature) is reached. At that point there is no net heat transfer — only microscopic energy exchanges that balance out.