# What bounces higher?

1. Nov 17, 2014

### TheExibo

Reading through my textbook, I came across a statement saying that dropping a ball onto the ground will result in the ground producing an impulse on the ball. Since impulse is the change in momentum, I figured that the momentum of the ball after the collision once it reaches the drop height is the same as before the drop. Would it be true that if you drop a light ball and a heavy ball at the same height, they would rise back up from the bounce to the exact same height?

2. Nov 17, 2014

### Simon Bridge

Try it and see - drop a ball and see if it bounces back to the same height it started from.
Try two different balls - do they bounce back to the same height as each other if they are dropped from the same height onto the same surface?

3. Nov 17, 2014

### Staff: Mentor

I wouldn't say its a light ball vs a heavy ball but rather a soft ball vs a hard ball. I think a golf ball will bounce higher than a rubber ball. Some of the impact is absorbed by the rubber and converted to heat meaning the ball won't bounce as high.

http://en.m.wikipedia.org/wiki/Super_ball

4. Nov 17, 2014

### TheExibo

Assuming they were made out of the same material, does the mass affect how high it bounces back up?

5. Nov 18, 2014

### DaveC426913

Yes, but for a practical rather than principled reason.

The more massive the ball, the more likely the impact will exceed its strength. It will deform (if not shatter). This means that you no longer have an elastic collision. Some energy will be lost in deforming the ball (and - for that matter- the ground).

6. Nov 18, 2014

### zoki85

"A Super Ball is observed to reverse the direction of spin on each bounce"

Interesting, I've played with them many times as kid, but haven't observed this effect.

7. Nov 18, 2014

### DaveC426913

Oh totally. One of the fun things you can do is throw it forward with a huge backspin. It will hit the floor six feet in front of you and counter-intuitively come straight back toward you! It'll bounce again at your feet and take off forward again, arcing back and forth with each bounce.

You can pretend you're bouncing it to someone, and they get ready to catch it, but instead it comes straight back to you like paddle ball.