Identical balls are dropped from the same initial height
Which surface exerts the biggest average force on the ball?
The average force acting on the ball is biggest in the with the cement floor case 2 when in the collision the ball bounces back to half of its initial height.
It is asked that in which case the average net force on the ball is highest.
According to impulse-momentum theorem,
Impulse I = F.Δt
where, F is the net average force and Δt is the time of contact during the collision.
In the case of collision with the rubber piece the time of contact of the ball and the ball increases by a large amount while in the case of cement floor the time of contact is very very less.
The change in momentum which is equal to the Impulse is also biggest in the case of cement floor because the transfer of kinetic energy of the ball in the case of cement floor will be almost immediate.
The bigger change in momentum and the smaller time of contact makes the average force on the ball is biggest in the case of cement floor case.
In which case the average net force on the ball is highest? The average net force on the ball is highest in the case where the ball bounces off the cement floor. This is because the change in momentum and the time of contact is greater in this case compared to when the ball bounces off a piece of stretchy rubber.