Here is a webpage with a number of videos, both experiments and matlab animations, of balls and people bouncing on a trampoline. Also, links to a paper in PLOS ONE.
http://movement.osu.edu/webpages_for_papers/seatdropwar2013.html
The interesting phenomenon is that when two balls are in simultaneous contact with each other, there is a dramatic energy transfer from one ball to the other.
Here is an article in Popular Science about the phenomenon:
Recent comments