- To illustrate how the coefficient of restitution of a ball effects height of bounce.
The two balls look alike but when dropped onto a hard surface the neoprene ball rebounds to almost 70 % of its initial height whereas the norsolex ball hardly bounces at all. The properties of the two materials (as stated on the manufacturer's specification sheet) are as follows:
Property
|
Neoprene
|
Norsolex
|
Tensile strength (kg f/cm2) |
205
|
124
|
Stretch (%) |
370
|
550
|
Hardness (JIS A) |
63
|
32
|
Restitution elasticity (%) |
53
|
3
|
Specific gravity |
1.39
|
1.25
|
- If one wishes they can use a meterstick to measure the drop and rebound height of the neoprene ball.
The manufacturer's information sheet states the following:
"The "Unhappy ball" is made of rubber called Norbornene polymer (brand name: Norsolex) which possesses excellent impact absorption properties. The rubber has great internal absorption of inputted energy and is able to dampen impact from a colliding object without giving the object a reaction force. It has the advantage whereby little resonance can be caused to occur by external vibrations. It can be processed in a similar manner to that of ordinary rubber, and sheets made of the material are utilized in a lot of applications.....
Watch a Collisions Demo: Happy and Sad Balls
video demonstration on Youtube
- Video Created at Utah State University by Professor Boyd F. Edwards and assistants.