BouncingBall is Abe's first attempt at a realistic simulation, which he wrote as part of his 5th grade science fair project. It is a discrete-time simulation and uses the stamp tool to show the position of the ball at each time step. The scale (in pixels per cm) can be adjusted with a slider, as can the coefficient of restitution for the ball. The background grid and axis labeling is done with the pen and stamp tools, since scratch does not provide an easy way for printing numbers on the screen.
This simulation has some problems with handling the overshoot when the ball hits the ground during a time step. The correct handling of that case is difficult in any simulation where the time step is fixed.