Zoetropes 1

I had an idea to show a ball falling for the Zoetrope. Now, this sounds really simple but I want to do it as accurately as possbile in that I show the acceleration of the ball as it falls and rebounds.

This is taken straight off Wikipedia (I know how terrible, but in this case it is accurate!)

"Under an assumption of constant gravity, Newton's law of universal gravitation simplifies to F = mg, where m is the mass of the body and g is a constant vector with an average magnitude of 9.81 m/s². The acceleration due to gravity is equal to this g. An initially stationary object which is allowed to fall freely under gravity drops a distance which is proportional to the square of the elapsed time. The image on the right [above in my case], spanning half a second, was captured with a stroboscopic flash at 20 flashes per second. During the first ¹⁄₂₀ of a second the ball drops one unit of distance (here, a unit is about 12 mm); by ²⁄₂₀ it has dropped at total of 4 units; by ³⁄₂₀, 9 units and so on."