Why does a basketball bounce back up?

A basketball falls, touches the floor, and jumps back up. The floor has not thrown it with a hand. It pushes on the ball while the ball changes shape. This tiny squash happens too quickly for our eyes to follow easily.

A basketball is a tough, stretchy shell filled with air. When it hits the floor, the bottom flattens a little. The shell bends and the trapped air is squeezed. Together, they act a little like a spring that has been pressed down.

As the ball returns toward its round shape, it pushes against the floor. The floor pushes upward on the ball. That push can send the ball back into the air. A very soft ball changes shape differently and usually gives a much smaller bounce.

Each bounce is usually lower than the last. Some of the energy spreads into warmth, sound, and movement in the floor. A player adds energy with a hand during a dribble. That is how the ball can keep bouncing instead of settling to a stop.