Hair dryer & ball

The upward pressure from the hairdryer balances the downward force of gravity, keeping the ball floating. It is possible to move the ball along with the hairdryer and angle it and so on. All this is based on the Bernoulli principle. This states that fast moving fluids are at a lower pressure than slow moving fluids. The airstream from the hairdryer is at a lower pressure than the air outside and ball that is smaller than the diameter of the airstream can therefore be balanced within it. If the ball starts moving out of the airstream to one side then the higher pressure of the air outside the airstream will push the ball back into the centre.

Bernoulli's Incompressible flow equation