A ball of mass m is dropped onto a floor from a certain height. The collision is perfectly elastic and the ball rebounds to the same height and again falls. Find the average force exerted by the ball on the floor during a long time interval.
Let the height from which the ball is dropped, be h.
Velocity of the ball before the collision = 
After collision, velocity of the ball = 
Taking v =
,
Time taken by the ball to hit the ground, t = v/g = 
Total time = 2t = 
Average force exerted by the ball on the floor = Rate of change of momentum of the ball
2