How do I create a time-dependent graph?

I want to create one of the simplest animations one can think of: A ball rolling down a hill. I can simulate the dynamics in about 4 blocks of Simulink model. When I run it, I'll get the results in the form of t, x(t), y(t). I can plot the graphs of x(t) and y(t), but what I really want is to show the position of the ball vs. simulated time.

I'm guessing this would be very easy to do, using MATLAB graphic functions, but I don't have a clue how to do it.

Ultimately, the graph will be turned into a GIF file.