[url=http://faculty.ifmo.ru/butikov/Pendulum/index.html]Free Oscillations and Rotations of a Rigid Pendulum[/url]
The Java-applet requires some time to load, so please be patient while it is starting. After the applet loaded, you can switch to off-line mode. The model allows us to observe the motion of the pendulum. You can vary the time scale by moving the slider (named "Delay" – down on the panel to the left side of the pendulum) for convenient observation. The model allows you also to display the graphs of time dependence of the angle and angular velocity (by checking the corresponding check-boxes on the same panel), as well as the graphs of energy transformations and phase diagram. You can resize and drag with the mouse the panels with graphs and the phase trajectory to any convenient place on the screen.
The panel on the right-hand side of the pendulum allows to vary parameters of the pendulum (absence or presence of viscous friction, and quality factor Q ), and also to change initial conditions of excitation (initial angle of deflection and initial angular velocity). You can change the values either by dragging the sliders, or by typing the desired values from the keyboard (editing the corresponding number fields). In the last case you should press "Enter" key after editing. The model will accept the new values after you press the button "Accept new values".