This demo sprang from an analysis of a simple bouncing ball simulation. In the initial version of the program, upon careful observation it could be seen that the ball bounced succesively higher on each bounce. The next step was to put a line in place to visually show the effect. Shrinking the simulation time step reduced, but did not elimate the problem (a basic piece of simulation knowledge, there). A detailed analysis of the algorithm showed the momentum at the bounce point was being improperly reversed. The middle and right ball illustrate variations on the improved algorithm.