A blue pool ball enters from the left hand side of the animation and collides with the stationary ball in the centre. Momentum and energy are transferred from the moving ball to the stationary ball. If the balls are considered to be hard spheres then the direction of momentum transfer is along the line joining the centres of the balls as they collide.

The animation shows the components of the momentum vectors of both balls. The final momentum of the balls in any direction should be equal to the initial momentum of the blue ball in that direction.

Use the FIRE button to start the animation.

Roll the mouse over different sections of the screen to reveal the momentum components of the balls. Check that the principle of momentum conservation is obeyed.