This model demonstrates Galileo's law of falling bodies. The distances travelled by a ball that, starting from the position of repose, rolls down an inclined plane, are proportional to the square of the time it takes to fall. This means that, if the ball descends for a certain distance in one time unit, it will descend four such distances in two time units, nine in three time units, and so on.

In this model, the time unit is marked by the semi-oscillations of a pendulum.