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Question

a pessenger jet in the air increases its speed does the downward force of air on the top of te wings

increase or decrease? does the net lifting force of the air on the wing increase or decrease? (Explain)

Answer 1

To first order, the lifting force is a function of the geometry of the wing and its speed.

The function of a wing is to redirect or deflect the air that is coming in horizontally to a downward angle. (Yes, this is an over-simplification)

For every action there is a reaction, so the more air is deflected and the faster that air goes down, the greater the net force up on the wing and hence the greater the lift.

All other things being equal (which they never are) doubling the speed of the wing through the air both doubles the amount of air that the wing deflects, and doubles the downward velocity of that air so the lift goes up as the square of the velocity.

On the other hand, the velocity of the air above the wing increases, so the pressure of that air decreases. Since the force of the air on the top of the wing is pressure times area and the area is constant, ...

http://www.grc.nasa.gov/WWW/K-12/airplane/lifteq.html
http://en.wikipedia.org/wiki/Lift_%28force%29