leaf blower
Aim a leaf blower staight up. Place a lightweight beach
or playground ball in the stream of air. The ball will be
suspended a few feet above the blower.
One of the principles involved is Bernoulli's Law which says
that the pressure exerted by a fluid moving along a surface
decreases as the velocity of the fluid increases. If the ball
begins to move out of the stream, the faster moving air along
the side of the ball that is toward the stream pushes less
than the slower moving air on the side of the ball away from
the air stream. So the ball is pushed back into the stream.
Volleyballs, soccer balls and other such thick wall balls are
too heavy. Only lighter balls will work. A size of 10 to 12
inches is suggested. Perform the demo outdoors to lessen
chances of damage and to provide adequate space. Leaf
blowers can cause ceiling tiles to be dislocated and to fall.