Chaos pendulum or Double pendulum
A chaos pendulum is a well-known physics demonstration that shows chaotic behaviour.
It appears random due to it being unpredictable owing to being highly sensitive to tiny changes.
Tiny differences with the pressure and speed of the push/release results in very different outcomes.
However…you may see repeated similar patterns from time to time and repetition, which is all very well documented by Chaos theory.
The Chaos pendulum can be configured in many ways, four standard arm/weight configurations are shown here. These are good starting points, but the kit of parts allows for a small amount of experimentation with the placement of the ring and arms, and a lot of experimentation with the placement of the four different weights.
Suitable for children 14 and above.