What you need:
• An empty bottle
What you do:
• Roll up a pea size ball out of foil.
• Place the bottle on the edge of a table.
• Put the ball of foil inside of the bottle neck.
• Try to blow the ball into the bottle.
What should happen:
• The foil ball shoots back out towards you.
Why does it happen:
•The same principles that keep airplanes in the sky also apply to this experiment. The key point is that moving air is at a lower pressure than still air. This is the Bernoulli Principle. In the case of the bottle the air that is blown towards the mouth is deflected around the the sides of the bottle (very little moves past the ball of foil). This means that the air pressure in front of the ball is lower than behind, and so the ball flies out.
Airplane wings are specially shaped so that air travels faster over the top of the wing than over the bottom surface. Again the pressure is lower above than below and the wing is “pushed” upward by the higher pressure air – called lift. The faster the plane moves forward the bigger the lift it experiences.