Watch some strange ways strong magnets interact with copper plates

[Otherbrother]

@fuzzyfungus

Moving the magnet when it is on top of the metal plate feels sort of like moving it through some sort of peculiar non-newtonian fluid: at very low speeds it feels almost the same as moving it again an ordinary surface; but the apparent ‘viscosity’ rises extremely sharply as you speed up; decreasing almost instantly when you slow down again. Very peculiar feeling.

This is exactly how eddy current brakes (now common on many roller coasters) work. They’re great because there are no brake pads to wear out. But since the effect goes away when speed approaches zero, mechanical caliper brakes are still needed to hold the train stationary.