I stumbled across this question in one of the physics competition selection test but after thinking like 2 days i still cant figure out hw to solve it. I've been introduced to the equation: entropy, S=Q/T where Q is the heat energy and T is the temperature. Then i've been told that the entropy of a system always remains constant or increase. Then the question is to show that when a hotter object and a colder object are put together and isolated the hotter object always becomes colder and colder becomes hotter. We are expected to solve this with the information provided only. Help anyone ?? ?