Why does increasing speed cause lift to increase?

Why does increasing speed cause lift to increase?

• A. The increased impact of the relative wind on the airfoil's lower surface deflects air downward.
• B. Increase in velocity reduces the pressure difference between upper and lower surfaces.
• C. Higher speed reduces dynamic pressure on the wing.
• D. The wing's curvature increases with speed, increasing lift.

Answer: (A)

Raising speed increases lift because the wing pushes more air downward as the air moves past it faster. When the glider speed increases, more air encounters the wing each second, and the airfoil deflects that air downward due to its shape and angle of attack. That downward deflection changes momentum of the airstream, and by Newton’s third law the wing experiences an upward reaction—lift. In addition, the overall lift rises with speed because dynamic pressure, which is proportional to velocity squared, increases; with more dynamic pressure acting on the wing, the wing can generate a greater upward force for the same size and orientation. The idea that lift comes from a greater pressure difference between the surfaces is related, but the key point is that faster air means more air is redirected downward and more momentum transfer per unit time, producing more lift. The other statements don’t fit: increasing speed does not reduce the pressure difference or dynamic pressure, and the wing’s curvature does not increase with speed in flight.

Raising speed increases lift because the wing pushes more air downward as the air moves past it faster. When the glider speed increases, more air encounters the wing each second, and the airfoil deflects that air downward due to its shape and angle of attack. That downward deflection changes momentum of the airstream, and by Newton’s third law the wing experiences an upward reaction—lift.

In addition, the overall lift rises with speed because dynamic pressure, which is proportional to velocity squared, increases; with more dynamic pressure acting on the wing, the wing can generate a greater upward force for the same size and orientation. The idea that lift comes from a greater pressure difference between the surfaces is related, but the key point is that faster air means more air is redirected downward and more momentum transfer per unit time, producing more lift.

The other statements don’t fit: increasing speed does not reduce the pressure difference or dynamic pressure, and the wing’s curvature does not increase with speed in flight.