Can you solve the MAGNET RIDDLE? ft YouTube CEO Susan Wojcicki

7:16 Hang them on the string (it helps a lot that the string itself is not magnetic). The magnet will "want" to stay in a particular orientation due to the Earth's magnetic field while the nonmagnetic iron "will not care". You actually need to make up to 3 experiments with a bar, one for each possible orthogonal orientation to be able to see the "want to orient itself" behavior because you may not know how the magnetic bar was magnetized. Also you might want to hold a pencil or something on that string to release the torque potential energy first.