Materials required: - an umbrella.
Fold the umbrella. Hold it horizontally. Run forward. Is it difficult or easy to run?
Open the umbrella. Hold it horizontally, Run. Is it easy or difficult to run now?
Why? Air resists the open surface of the umbrella. But when closed it is like a wedge
piercing through the air. In the beginning the front side of a motor car was flat surfaced. So there was a great air resistance for the moving car. But gradually they have changed the shape like the shape of a fish. This kind of cars are called ’stream lined cars’ When they move air passes over the front and slide smoothly offering less resistance and hence the car can move with a great speed.

TAG: air resistance, science fair projects, umbrella

Materials required: - a balloon with noise producing reed attached to it and a tub of water.
Blow the balloon. Hold the end of the tube tightly and do not let the air leak out. Lay the blown balloon on the surface of water in a tub or  bucket and re­lease your hand. The balloon moves now forward. It may even move round and round if it is placed in a big bucket. Air coming out of the balloon pushes the balloon forward.
In fire works you must have seen how the rocket shoots up its fire and smokes backward; the toy rocket shoots up in the air.
In a jet plane there is no propeller or fan. Hot air from inside shoots out backwards and the plane is pushed upwards.

Materials required:- a glass funnel or plastic funnel and a Ping-Pong ball (or small ball made from a torn balloon)
With your right hand hold the broad side of the funnel downward. Hold the ball in your left hand. Blow hard into the funnel and remove your hand from the ball. See how the ball hangs freely in the air within the funnel. Is it magic or juggling? Stop blowing. Does the ball float in the air still? Sure, you will like to repeat it many times.
What is the secret of it? Blow the air above the ball. It moves away due to the less air pressure; the air below the ball has more pressure than the air above. So it lifts u p the ball. W hen you stop blowing air pressure above and below the ball is the same. Hence the ball falls down due to its own weight.