A cylinder is divided in half by a movable disk in the middlEach half is filled with an equal number of gas molecules, but one half is at a higher temperature than the other. Which choice best describes what happens next?
(a) Nothing.
(b) The high temperature side expands, compressing the low temperature side.
(c) Heat moves from hot to cold, so the low temperature. side will gradually increase in temperature and expand
(d) (b) happens quickly, but after that (c) happens more slowly.

Video Transcript

This is College Physics Answers with Shaun Dychko. A cylinder is divided in half by a movable disk that I have drawn in blue here and each half is filled with an equal number of gas molecules. But one half is at a higher temperature than the other. So let’s say this is a high temperature and this is a low temperature and if that's the case then these gas molecules will expand and push this movable disk downwards and so that means part B is going to happen. Now what will happen slowly is that the some heat will transfer from the high temperature to the low temperature and cause the high temperature region to slowly cool and then the cold temperature will slowly warm and which case the gas in the bottom will slowly expand and the gas in the top will slowly contract and so C is also true. So that means we take D that says that B happens quickly, but after that C happens more slowly.