Many people have seen the acrobatic item of Flying Vehicles on the Walls. This performance is staged in a round wooden barrel with a diameter of about 30 meters and the walls of the barrel are nearly upright. On the steep inner walls, performers can ride bicycles, motorcycles and even cars. What's the secret behind it?

We all know that any object in circumferential movement is affected by centrifugal force. The magnitude of the centrifugal force is decided by the moving speed -- the faster the speed, the bigger the centrifugal force.

This principle of centrifugal force is applied in Flying Vehicles on the Walls. When the performer(s) ride bicycles, motorcycles or cars on the walls of the barrel, the tires of the vehicles press the walls hard and roll forward along the walls with the combined effects from gravitation and centrifugal force. The key here is the speed of the vehicles.

Only those bicycles that reach the speed of 35 kilometers or above per hour can be used in this performance. Though performer(s) can step on the gas to speed up motorcycles and cars, they should be skilful and good at maneuvering the vehicles because motorcycles and cars are heavier and have bigger convulsing force.