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WHY?
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Look at an airplane wing from the edge. You see a shape in which
the top of the wing is quite curved. When in flight the position of the
wing is set at an angle so that air hits the bottom of the wing. The
moving air then creates a high pressure under the wing. A pressure
difference with a lower pressure on top and a greater pressure below
creates the net upward force of lift on the wing. The lift of a wing can
be increased by tilting it upward at an angle to the air flow. This
gives the wing a greater angle of attack. There is an angle of attack
(usually about 18 degrees) at which lift is greatest. If the angle of
attack is made too large, the air will no longer flow smoothly over the
wing and lift will become less. The other force acting on a wing from
the flow of air is drag. The drag acts to slow the speed of the wing
through the air. If there were no drag, an aircraft could just keep
going faster and faster. A flat wing, like one you would make for a
paper airplane, can create lift if given some angle of attack. It will
have greater drag for the same amount of lift than a properly curved
wing.
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ASSESSMENT: Can the student communicate
what they observed?
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