# HRK Energy/Rotational Motion Question

1. Sep 21, 2011

### conquerer7

1. The problem statement, all variables and given/known data
A concept question from Halliday, Resnick, Krane:
"A disgruntled hockey player throws a hockey stick along the ice. It rotates about its center of mass as it slides along and is eventually brought to rest by the action of friction. Its motion of rotation stops at the same moment that its center of mass comes to rest, not before and not after. Explain why."

2. Relevant equations
None. I suppose the answer should be intuitive!

3. The attempt at a solution
I've tried but I have no idea how to go about doing this. It's extremely different from any other question they give...

2. Sep 21, 2011

### Delphi51

Would it have anything to do with the fact that the kinetic coefficient of friction is different from the static one?

3. Sep 21, 2011

### conquerer7

I doubt it- it's always kinetic friction until both rotation and translation stop, right?

4. Sep 22, 2011

### Delphi51

Yes. I guess it isn't a way one of the motions would affect the other directly.
Another thought - the spinning makes one end go faster, the other slower. At some point on the slower side, the speed with respect to the ice would be zero - higher friction force affecting the rotational motion. It might be worth thinking about how this changes as the translational speed gets smaller.