# Ball colliding with rod elastically

1. Jul 13, 2016

### Vibhor

1. The problem statement, all variables and given/known data

Ans D)
2. Relevant equations

3. The attempt at a solution

The problem I am having in this question is that mass and speed of ball is not given . I think it is not possible to solve this question without this data .

Am I correct or is data sufficient in this problem ?

Thanks

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2. Jul 13, 2016

### PeroK

Just make something up for the mass and speed of the ball and see what answer you get. Then, try a different mass and/or speed, and see whether you get the same answer.

PS Do you understand what they mean by "instantaneous axis of rotation"?

Last edited: Jul 13, 2016
3. Jul 13, 2016

### jbriggs444

You can save yourself some calculation by ignoring the ball and the statement that the collision is elastic. The important information is that the rod has had an impulse applied at one end at right angles to its long axis. The ball and the rebound speed required to conserve total energy are an irrelevant distraction.

4. Jul 13, 2016

Thanks a lot