I came across the following question in a first-year physics examination from Cambridge (Part 1A Natural Sciences) and, since I have posted anything in the Cute Problems folder for a while I thought I would share it here:
Answers through the comments box please! And please show your working!
P.S. The preamble does not say whether you can also assume irrelevant formulae without proof…
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I heard this nice physics problem today so I thought I’d try it out on here. You will probably be able to find the answer on the net somewhere but please try to figure it out yourself before doing so!
There are two identical chambers, A and B containing identical metal balls which begin the experiment at the same temperature. Apart from the balls, each chamber is a perfect vacuum and has thermally conducting walls at a lower temperature than the ball it contains.
In A the ball is resting on the floor, which is made of material which is a perfect thermal insulator.
In B the ball is hanging from the ceiling by a piece of light inextensible string, not touching the floor. Both the string and the ceiling are also made of perfectly insulating material.
Which ball cools down faster?
Please put your answer through the poll here. When enough people have voted, I’ll tell you the answer…
In the Dark 