Uploaded Jan 10, 2014
An inverted pendulum is in unstable equilibrium.. left to itself, it will topple out of equilibrium.
However, if you apply a vibration with a suitably high frequency to the base of the pendulum, you can stabilize it.
Try it here. ω is proportional to the frequency. A value of 1 does not stabilize the pendulum. What value does?
This is one of the 77 physical paradoxes in Mark Levi’s book Why Cats Land on their Feet.