This is mainly a script you can use in other projects. The ball can be thrown around by dragging it. As soon as you release the mouse, the ball will fall down and bounce. Every time the ball bounces it looses a little bit of it's speed. You can adjust this by changing the variable "damping". You can also adjust the gravity, by changing the "accelleration" variable. To make the ball fall down, the number must be negative. You could try to make the ball fall up. Or set the accelleration to 0. The ball would just bounce, without falling in any particular direction. For some reason, the project doesn't work well in the editing mode (some variables aren't updated correctly).
