perplexus.info :: Science : Balls of confusion

Balls of confusion (Posted on 2005-04-05)

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?

Submitted by Hugo

Rating: 4.3333 (3 votes)

Solution: (Hide)

The one on the table.
When the heat is applied, the ball on the table will expand and in doing so, its center of gravity will become higher. Because of that, the potential energy of the ball will raise. The energy needed to raise the potential energy will be deducted from the heat. Consequently, the balls temperature will be slightly lower than the temperature of the hanging ball. I recommend to also read Ajosin's comments.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
Puzzle Thoughts	K Sengupta	2023-02-21 23:39:09
hypothesis	Jud	2005-08-11 12:46:23
re(3): Just a question + To Ajosin	ajosin	2005-04-14 14:01:54
re(2): Just a question + To Ajosin	ajosin	2005-04-13 23:46:44
re: Just a question + To Ajosin	Hugo	2005-04-08 19:39:26
Just a question	Leming	2005-04-08 00:42:49
re: Another guess (solution?)	john	2005-04-06 18:14:30
re: Another guess (solution?)	np_rt	2005-04-06 02:07:38
Another guess (solution?)	ajosin	2005-04-05 23:07:07
My guess	Bryan	2005-04-05 21:44:42
re: Height?	Hugo	2005-04-05 15:41:31
Height?	brianjn	2005-04-05 04:07:59

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