Balls bounce due to the elasticity of the material they are made from. The best materials for bouncing are the ones that can stretch like an elastic band and then go back to their original shape quickly and easily. Some materials, like rubber, are very elastic, and therefore bounce easily.
When a ball hits a hard surface, its shape will change. It tends to flatten or deform. This flattening happens for only a fraction of a second, and then the ball returns to its original shape. This flattening happens too quickly for our eyes to see.
When the ball flattens, it gains energy. When the ball returns to its original shape, this energy causes the ball to bounce up, the opposite direction to the original falling motion. As the ball bounces, it loses energy and will gradually slow down and finally stop.
Elasticity is a very important property of many materials, objects, and things we use every day. For example, some clothes may have an elastic waist band fitted into them so they fit better. As well, the muscles in our body have special elastic properties that allow us to perform activities and bend our bodies in different ways. Think about the plastic lining around doors, your running shoes and even your X-Box controller. Without elasticity, we may not be able to use or do things that we enjoy daily. Here are some technical uses of plastic that require elasticity:
The Grand Bounce LAB
VIDEO #1: CORNSTARCH AND WATER
VIDEO #2: Glue and Borax