# Tennis Ball Vs Glass Ball Vs Rubber Ball

1. Oct 18, 2005

### kecontroversy

HI guys. im facing a problem that is quite interesting but quite complicated to explain. so would like to ask some help.

the problem is talking about the boucebackability of three different balls. Tennis ball , glass ball and rubber ball.
there is one little boy claims that the glass ball will bounce higher than rubber ball and the rubber ball will bounce higher than the tennis ball..

and there is boy saying that the tennis ball will bounce higher..

so who's right???

erm... i know that this problem is sumthing related to elastic collisions and about kinetic energy.. i mean the conversion of the energy.
but im not sure how am i going to explain the fact..
and what are the things i have to take into consideration.
thux...

2. Oct 18, 2005

### brentd49

The only variable, assumming the balls are thrown at the same speed and ignoring air resistance, is k, the spring constant. I suppose in the lab you could measure k by measuring the Force required for a certain displacement, i.e. F/x. Though, I think this might be rather difficult for glass which would mostly likely break on impact anyway.

3. Oct 19, 2005

### Intuitive

Last edited by a moderator: Apr 21, 2017
4. Oct 20, 2005

### pervect

Staff Emeritus
A lot is going to depend on the surface the ball strikes. The glass and solid rubber balls will be very "hard", and might underperform a tennis ball on a soft surface (like a grass or clay tennis court). On a harder surface though, the reverse might well happen.

If the ball is harder than the surface, the characteristics of the surface will be the most important for determining the bounce height, as it is the surface that will deform most. If the surface is harder than the ball, the reverse is true. If the ball and surface have the same hardness, then it will depend on the elasticity (energy-conserving properties) of the material, and the magnitude of the peak force. Most materials will be reasonably elastic if the force is below some critical value, the "plastic limit". If the force exceeds this limit, the object will lose significant energy via plastic deformation.

5. Oct 20, 2005

### Staff: Mentor

This question is easy to settle experimentally, of course. In our "descriptive physics" course we have a lab experiment in which students measure and compare the "rebound heights" of various kinds of balls on a metal surface.

Everybody laughs when they get to the lead ball, which doesn't rebound at all. It just plops down with a dull "thud" sound instead of a "bing."

6. Oct 20, 2005

### pallidin

Liquidmetal ROCKS! I saw the web site some months ago, and I would recommend all to view the videos.
I also found out through the web site that SanDisk has a "thumb drive" that's case is made out of this. It's the Cruiser Titanium series.

Last edited by a moderator: Apr 21, 2017
7. Jun 20, 2008

### rcgldr

Try susbstituting a billard ball for the glass ball, since a billard ball bounces very well on hard surfaces and won't break (within reasonable impact speed range).

Regarding the liquid metal ball, the surface that the balls were bouncing on wasn't described. It could turn out that the other materials would bounce just as well as the liquid ball if bounced on a different surface, such as hard marble (not metallic to make it fair).