Loop of death

Have you ever seen a motorist in a circle who rides upside down in a 'Devil's circle? How does it come that he never falls down?

The force which squeezes the motorist to the path, in particalar at the highest point of the circle is called the centripetal force. The same force makes a car skid on a bend on a slippery road.

In order not to fall, the motorist has to start the ride from a place two and a half times higher than the highest point of the circle.