How Does Bounce Change Direction?

Most recent answer: 12/17/2015

when you drop a steel ball bearing onto a concrete floor it bounces. does the ball stop before it changes directions. thank you very much for your time.
- stephen kelly (age 29)
clinton tn usa

If you look at the average velocity of the ball, as it smoothly changes from down to up it must go through zero. The trick here is that the ball isn't rigid so that different parts have different velocities during the bounce. The bottom part changes its velocity first. At the moment that the average velocity is zero the top is still going down and the bottom has started to go up, so the ball is squashing flatter. After the bounce is over, the ball's shape still shakes around some, with that energy gradually going into just heating it up a little.

Mike W.

Here's a nice background thread: .

(published on 12/17/2015)