Free Fall models a ball that is dropped or thrown near the surface of Earth. Newton's second law states that a force F produces an acceleration a that is proportional to the mass m of the falling object.
F = ma .
A freely falling object is acted on by a constant downward gravitational force if we ignore air resistance. Because this gravitational force F is constant and because it is proportional to the mass of the falling object, all objects near Earth fall with the same constant downward acceleration g = 9.8 m/s2. In the Free Fall model, the ball's speed is reduced by a constant factor at every floor collision. All motion takes place in the vertical (y) direction to keep this first Ejs example as simple as possible.