What is momentum?
Two balls X and Y, with the same diameter but masses of $0.24\,\text{kg}$ and $0.12\,\text{kg}$ respectively, move towards one another on a frictionless horizontal surface, as shown in Fig. 2.1. Before they collide, both balls have a speed of $2.3\,\text{m s}^{-1}$. Fig. 2.2 shows how the force $F_Y$ acting on ball Y due to ball X changes with time $t$ during the collision.
Calculate the kinetic energy of ball X before the collision.
The region enclosed by the lines and the time axis in Fig. 2.2 gives the change in momentum of ball Y during the collision. Find the magnitude of the change in momentum of ball Y.
Calculate the magnitude of the velocity of ball Y after the collision.
On Fig. 2.3, sketch how the force $F_X$ exerted on ball X by ball Y changes with time $t$ during the collision in (b).