2.7 Double pendula
Another example of chaos is the motion of a double pendulum. This is a pendulum which is suspended from a fixed point, with a second pendulum attached to the end of the first pendulum. In contrast to the regular oscillations of a single pendulum (such as a pendulum on a longcase clock), the oscillations of a double pendulum can rapidly become unpredictable and chaotic, and the motion can exhibit extreme sensitivity to initial conditions.
You can see examples of this behaviour in these two video clips. In the first one, in which a single double pendulum is released from above its resting position, the behaviour of the pendulum soon becomes unpredictable.
In the second one, in which two identical double pendula are released from virtually the same starting position, the two pendula begin to behave differently almost immediately.
