Drop the magnet down the tube with its flat sides facing up and down. Hold the copper pipe the same way and drop the magnet just the same. The magnet will fall straight down the plastic pipe and ...

A magnet sliding down a copper ramp is slowed by magnetic fields from eddy currents induced in the tube. A magnet sliding down a Plexiglas ramp is unaffected. A magnet sliding down a brass ramp goes ...