Marvin & Milo
What you need:
Four or more small magnets
String or strong thread
A horizontal rod e.g. a pencil
A flat surface
Fix the rod in place and hang one magnet from it to make a pendulum. (Keep magnets away from toddlers!)
Tape the rest down in an equal-sided pattern e.g. a triangle or square.
With the pendulum very close to the magnets, give it a gentle push. Try changing its starting point, or swinging it harder.
Results & explanation
The pendulum will move weirdly, maybe reversing or hanging around one magnet before settling above another. A slight change to how you start it off will make a big difference to where it ends up.
Gravity, the magnetic attractions and pushes on the string work together in complicated ways so that it’s very difficult to predict how the pendulum will swing or where it will settle, even though it’s following the laws of physics.
See previous cartoons
Free fall ride
See more on physics.org