# Homework Help: Investigating the Phenomenon of a hot Ball on Parallel Metal Rails

1. Nov 6, 2008

### mrh1192

1. The problem statement, all variables and given/known data
Put a hot metal ball on parallel horizontal rails. The ball starts to move. Investigate the phenomenon.

2. Relevant equations
I have found two equations, one exponential and one linear relating the expansion of the rails and the ball to the temperature increase.

3. The attempt at a solution
I have been working at this problem for more than 3 weeks now. I have tried heating up the rails and ball separately to try and measure their expansion, and have tried the experimental set up numerous times however the ball simply won't move. I have tried heating the ball when it is on the rails, to try and induce some movement however this hasn't worked either!! Aluminium rails are being used, with a stainless steel ball bearing. However, the temperature of the apparatus at the point where the ball sits eventually gets so high that the rails begin to deform, preventing the ball from moving.

Does anybody have any ideas how this phenomenon works, or how I could improve the set-up in order to make it work?

Thanks

2. Nov 6, 2008

### nasu

Something is missing here.
So you don't see the ball moving so far. How do you know that it is supposed to move?
But assuming that is will, if the rails are horizontal and the ball is spherical, which way will the ball move? (Right or left, for example)

3. Nov 6, 2008

### mrh1192

We know that the ball should move because the problem (see above) states that it should. Which direction it moves in is also unknown, though I assume it could roll either way. I am not sure whether any factor affects it's tendancy to move right or left, and no experimentation so far has suggested that there is a specific tendancy.

Do you think that there may be somethnig unknown behind this problem?