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?

supposing that these metal balls expand, the one on the table will be performing work, against the force of gravity, thereby storing some energy as gravitational potential energy. therefore, one would expect the ball on the table to have a lower temperature. however, this is not guaranteed.  It is possible that the other ball expands to a different pressure due to its ability to lower its center of gravity.  Depending on this pressure, the temperature of the hanging ball could hypothetically equal or drop below that of the ball on the table.

Posted by Jud on 2005-08-11 12:46:23