1. The problem statement, all variables and given/known data A superball is to bounce elastically back and forth between two rigid walls at a distance d from each other. neglecting gravity and assuming the velocity of superball to be horizontal .Find the average force being exerted by the superball on each wall is ? 2. Relevant equations 3. The attempt at a solution We consider rightwards direction to be positive . If the ball moves at velocity v towards right wall then after collision it moves with velocity -v towards right. The change in momentum of the ball is -2mv .The change in momentum of the wall is 2mv . But we do not know the time of collision , so how do we calculate rate of change of momentum and hence force ?