# Homework Help: Coefficient of Restitution

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1. Oct 6, 2015

### Arlan

Question: The coefficient of restitution for ball colliding with steel is 0.95. If ball is dropped from height h sub o above steel plate, to what height will the ball rebound?

Please help me with this one, Is there a formula for this? all I know is e equals velocity of the first object subtract to velocity of the second object divided by the velocity of the second object subtract to velocity of the first object.

2. Oct 6, 2015

### haruspex

So apply the formula you know to the situation. What are the velocities here?

3. Oct 6, 2015

### JBA

I believe this is a thought question with no equation required. You are over complicating it. Lookup:the definition of "Coefficient of Restitution" and I think you will realize the quick answer.

4. Oct 6, 2015

### Arlan

there are no velocities given, but thanks

5. Oct 6, 2015

### Arlan

I'll do that. thanks for helping

6. Oct 6, 2015

### haruspex

You must not let that block you. Many questions appear not to provide enough information, but if you simply plug in unknowns as necessary you may find they later cancel.
In the present case, however, you are effectively given the velocities. You know the height from which the ball is released, so you can find the impact velocity. You also know the velocity of the ground before and after, so you can use the restitution factor to find the rebound velocity of the ball. Etc.

7. Oct 10, 2015

### Arlan

okay. I'll keep that in mind. thanks