Collisions A collision is a brief interaction between two objects. Collisions can be of two types inelastic and elastic collisions. An inelastic collision is a collision between two objects that collide and are then stuck together moving with an equal final velocity. Elastic collisions deal with objects that collide and then split apart moving with two separate final velocities. In the sport of racquetball we will be dealing with elastic collisions. http://www.hiviz.com/tools/cameras/video/video_pt4.htm Collisions are very important in racquetball as it is a game of collisions, the racket with the ball, the ball with the wall, the floor and ceiling. All of these are elastic collisions, an elastic collision is one where momentum is conserved that is the final momentum after the collision is equal to the initial momentum before and total kinetic energy of the system is also conserved. http://www.keyword-suggestions.com/cmFjcXVldGJhbGwgcmFjcXVldCBhbmQgYmFsbA/ As the ball collides with the racket the momentum of the racket is transferred to the ball, the ball then accelerates at much greater rate due to its smaller mass. As the ball collides with one of the walls the ceiling or the floor the ball exerts a force on the wall transferring its momentum to the wall, the wall then accelerates very slightly, so slightly that it is unperceivable due its mass that is much much greater than the balls. The wall also exerts a reactionary force back on the ball causing the ball to rebound in the opposite direction, and momentum is conserved