The bounce of a ball is a seemingly innocuous event that can be used to illustrate many aspects of
elementary and even advanced mechanics. Both normal and oblique bounces on a rigid surface are
considered in this article, emphasizing qualitative features of the bounce process. If the ball
bounces at an oblique angle then it can slide throughout the bounce, or just at the start of the
bounce, and may even slide backwards at the end of the bounce. A ball can also grip the surface
after a short sliding phase, or it can grip right from the start. When the ball grips, static
friction rather than sliding friction determines the rebound speed, spin and angle.