In a room there are two completely identical metal balls. One is lying on a table and the other is hanging on a cable attached to the ceiling. At the same moment, 1 Joule of heat energy is applied to each of them. Immediately after that, the balls are perfectly insulated, such that absolutely no heat transfer is possible.
Which one is the coldest?

The one on the table is coldest.

Both balls expand. This means that the one hanging will lower it's center of gravity and the one on the table will raise it. In the end, the ball that is hanging has more internal energy because of this change of potential energy, so the one on the table is the coldest.

This is a tiny effect however. You could not even begin to measure in real life.

Posted by ajosin on 2005-04-05 23:07:07