Non-Linear pendulum

*To*: mathgroup at smc.vnet.net*Subject*: [mg104874] Non-Linear pendulum*From*: Allamarein <matteo.diplomacy at gmail.com>*Date*: Thu, 12 Nov 2009 06:04:33 -0500 (EST)

I'm getting to know Mathematica. I want to compile a code to see the non-linear pendulum behavior. pendulum= {Line[{{0, 0}, {0, -1}}], Circle[{0, -1.3}, 0.3]}; l = 20; g = 9.81; s = NDSolve[ { \[Theta]''[t] == -g /l Sin[\[Theta][t]], \[Theta][0] == Pi/2, \[Theta]'[0] == 0}, \[Theta], {t, 0, 30}]; Animate[ Graphics[Rotate[pendulum, \[Theta[]t], {0, 0}], PlotRange -> {{-2, 2}, {0, -2}}], {t, 0, 30}, AnimationRunning -> False] This code doesn't work. I realized my error is in Rotate argument. If I change this line with: Graphics[Rotate[pendulum, Sin[t], {0, 0}] code runs, but it's not the result (obviously). How can I correct my code, to see the pendulum oscillates with \[Theta] [t] law?

**Follow-Ups**:**Re: Non-Linear pendulum***From:*Mark McClure <mcmcclur@unca.edu>