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