The ball placed in the stream of hot air from the drier hovers freely. The ball vibrates sideways but does not fall down. This means that, according to Newton's laws of dynamics, the forces on the ball counterbalance each other (gravity is counterbalanced aerodynamic lift of the hot air). It is somehow similar to a uniform fall of a parachute jumper, the only difference being that the air flows and the ball hovers in place.

Why is the point of equilibrium situated in the middle of the air stream where there is the greatest velocity and the ball should theoretically be blown away? This phenomenon is explained by so called Bernoulli's principle. The principle says that where the velocity of flow is greater, the pressure is smaller. The smaller pressure in the centre of the current sucks the ball in.

The same principle explains why planes fly in the air.

Newton was keenly interested in the phenomenon of air resistance and he introduced well known 'c' coefficients of aerodynamic resistance.

The values of these coefficients are: 0.8 for a cylinder, 0.47 for a sphere, 0.2 for a bullet. A parachutist relies on increased air resistance when falling down. Formula-1 racing cars are fitted with specially designed wings, which provide additional pressure to the wheels pushing them against the ground (and increasing the force of friction).

The balls on the films hover in the stream of air. Pushed from the side the balls return to the middle of the stream. It seems they reach the state of permanent balance, like always-up doll, the dancing dog's head, or like levitron in a well of the magnetic field.