This is a simulation of the position of a ball that was thrown with an initial velocity chosen by using the slider. The initial velocity can be negative or positive, where negative velocity means you throw the ball straight down. When the ball hits the ground, the ball bounces. In the interest of simplicity, this model has not been designed to accurately capture the true physics of a bouncing ball. In particular, as the size of the bounce decreases, this particular model does not accurately represent the physics. As a result, if you were to run the simulation out for a longer time period, you would notice that the ball never stops bouncing! An excellent exercise would be to build a model which correctly captures the fact that the ball eventually runs out of energy and stops bouncing.