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Wings give an airplane lift, but they do not drive it forward. In some airplanes, the propeller (turned by an engine) drives the plane forward by pushing the air backward. The air, reacting to the action of the propeller, pushes it forward. (For every action, there is an equal and opposite reaction - Newton's Third Law of Motion.) As the propeller is attached to the plane, it pulls the plane through the air.
Use a small electric fan with a very long extension cord for a propeller. Put the propeller on anything that can move easily - a wagon or a roller skate. Sit it firmly on the roller skate or wagon. The fan drives the wagon or skate backwards. This is because the blades are set to throw the air in front of the fan.
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Updated: March 12, 2004