
One good way of making an animation is by simulating a physical system and illustrating the variables in that system using a dynamically changing graphical display.

The classic such physical system is a simple gravity pendulum.



Task

Create a simple physical model of a pendulum and animate it.




freq = 8; length = freq^(-1/2);
Animate[Graphics[
  List[{Line[{{0, 0}, length {Sin[T], -Cos[T]}} /. {T -> (Pi/6) Cos[2 Pi freq t]}], PointSize[Large], 
               Point[{length {Sin[T], -Cos[T]}} /. {T -> (Pi/6) Cos[2 Pi freq t]}]}], 
  PlotRange -> {{-0.3, 0.3}, {-0.5, 0}}], {t, 0, 1}, AnimationRate -> 0.07]