Question
Tue September 25, 2012 By:

A ball is dropped on to the floor from a height of 10m. It rebounds to a height of 2.5m.If the ball is in contact with the floor for 0.01s, what is the average acceleration during contact?

Expert Reply
Thu September 27, 2012
velocity of the ball just before contact:
u = -(20g)1/2    using energy conservarion, i.e equating PE at top with KE at bottom
 
velocity of ball just before leaving ground:
v = (5g)1/2
 
thus force imparted to ground :
F = M ( (5g)1/2  + (20g)1/2   )/0.01  the direction of force is downwards.
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