Coefficient of Restitution (cor) of 3 Balls

How does the COR affect different types of sports balls bounce on different types of surfaces?

AIM - the aim of this experiment is to find out how the COR (coefficient of restitution) of 3 balls (tennis ball, snooker ball and ping pong ball).

FORMULA USED FOR COR -

GPE (after) = KE (after)

GPE (before) = KE (before)

mxgxHr = Ð... x mx VoutІ

mxgxHd Ð... x m VinІ

Hr = VoutІ

Hd VinІ

APPARATUS-

* meter stick,

* tennis ball,

* ping pong ball,

* snooker ball,

* surfaces; wood and carpet

METHOD - I will firstly organize all the apparatus that are needed for this experiment.

1. I will make 3 tables for my results to be recorded in.

2. Then I will get my partner to hold the meter stick firmly with one hand.

3. In the other hand of my partner, the first ball will be held.

4. My partner will drop the ball from a height of 100cm.

5. I will keep at eye level and watch closely

6. I will record the height, to the nearest cm, of the highest point that the ball bounces to.

7. I will repeat this method ten times on wood, and then ten times on carpet.

8. I will then bring into play the two other balls, and do the same as I have done with the first ball.

PREDICTION - I predict that the tennis ball will bounce higher on wood than the other two balls. Reason being that the tennis ball is lighter than the snooker ball and requires less force. The material used is also a factor that will help it bounce higher than the ping pong ball.

RISK ASSESMENT -

Item Risk Reduce hazard Implementation

All balls used

(football, tennis ball, ping pong ball) Some balls may be heavy and hurt someone Be sure to keep a safe distance When I let go of the ball, I made sure I moved back.

There were no other significant hazards.

DIAGRAM OF EXPERMIMENT-

Results -

Tennis Ball -

On carpet (cm) On wood (cm)

1st bounce 45 47

2nd bounce 44 55

3rd bounce 43 56

4th bounce 45 45

5th bounce 43 52

6th bounce 51 53

7th bounce 43 52

8th bounce 42 56

9th bounce 43 54

10th bounce 44 53

Average 44.3 52.3

COR 0.67 0.72

Average on Wood =

47+55+56+45+52+53+52+56+54+53 = 523cm/10 = 52.3 cm

Anomalous = 51

COR = 52.3 / 100 = 0.72

Average on Carpet =

45+44+43+45+43+51+43+42+43+44 = 443cm/10 = 44.3cm

Anomalous = 47, 45

COR = 44.3 / 100 = 0.67

I can say, by observing my table of results, the ball bounces higher on the wooden surface in comparison to the carpeted surface.

Ping pong ball -

On carpet (cm) On wood (cm)

1st bounce 43 54

2nd bounce 42 58

3rd bounce 58 59

4th bounce 43 52

5th bounce 45 55

6th bounce 42 54

7th bounce 46 55

8th bounce 43 44

9th bounce 43 52

10th bounce 44 54

Average 44.9cm 53.7cm

COR 0.67 0.73

Average on Carpet =

43+42+58+43+45+42+46+43+43+44

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