This Java applet demonstrates the variation of elongation, velocity,
tangential acceleration, force and energy during the oscillation
of a pendulum (assumed with no friction).
The "Reset" button brings the body of pendulum to its initial position.
You can start or stop and continue the simulation with the other two buttons.
If you choose the option "Slow Motion", the movement will be five times slower.
The length of the pendulum, its mass and the amplitude of the oscillation
can be changed within certain limits. In order to select another physical
size you have to click on the appropriate one of the five radio buttons.
The insignificant dependence of the oscillation period upon the amplitude
was neglected in the calculations.