# Homework Help: Momentum and Collsions

1. Jan 11, 2008

### Zarbon

I have a doubt in repetitive collision problem. A spherical mass m is striking the ground from a height h. The coefficient of restitution b.w ground and the spherical ball is e. If n collisions take place before coming to rest.
1)What is the total distance covered by the spherical ball before coming to rest. (There is no friction between ground and the ball. )
2) Total number of collisions
3)the total time taken after n collisions.
4)the total change in momentum after n collsions.

2. Jan 11, 2008

### Gokul43201

Staff Emeritus
That's a standard textbook question (though, the statement about 'n' collisions is only an approximation). So what exactly is your doubt regarding this? We can not help you unless you first show some effort. And please read the posting Guidelines.

3. Jan 11, 2008

### Shooting Star

First, you should find out how much of the original height the ball jumps back to from which it was dropped.

(Hi Mentor, Pl shift this to the HW forum.)

4. Jan 12, 2008

### Caesar_Rahil

First calculate how much height it will rise after it's first collision (I hope you can do this), then find out for the second, then third.
by now, you may have started noticing an interesting pattern in the heights (I won't spoil the fun, find out yourself)

5. Jan 12, 2008

### Shooting Star

He has to calculate just once to what fraction of H is the ball jumping back to. If that fraction is a constant, he does not have to calculate for n times.