Two rigid simple pendulums 
The main interest of this applet is to allow the «experimental» comparison of the movement of two pendulums, where only one of the parameters is different (between the 2 pendulums).
This applet uses Javaview
If you have difficulties viewing the applet, click here
Here are some examples, among many possible others:
Two pendulums that only differ in mass, although they have different energies, have exactly the same motion if there is no friction, but they move in a different way when there is a friction.
Two exactly identical pendulums have very close periods for small oscillations, even though the maximum amplitude of one is about twice that of the other.
But the same is not true for large oscillations: for example, changing only the values of the initial velocities in the previous example (to 1.1547 and 1.14, respectively), the period of the first becomes more than twice the period of the second.
If two (frictionless) pendulums only differ in length and if the ratio of their lengths is 4,
one has a period which is twice that of the other. (To minimize interference of numerical approximation errors, it is convenient to choose oscillations which are not too big.)
Note1: For more information, consult the help.
