A ball of mass m bounces horizontally back and forth between two heavy vertical walls, each of mass M>>m. The separation between the walls is L and the kinetic energy of the ball is K (assume that it does not decrease, i.e. that the collisions are always elastic). Find the average force on each wall. HINTS: It will help to first answer two questions. What is the impulse given to a wall during one bounce? How many bounces occur in a given amount of time t?