Which statement correctly describes how lift is produced on a wing?

• A. Lift occurs due to a pressure difference with higher pressure on the lower surface and lower on the upper surface.
• B. Lift is solely due to gravity.
• C. Lift is produced by capturing more air molecules on the top of the wing than the bottom.
• D. Lift is an effect of propulsion not aerodynamics.

Answer: (A)

Lift comes from a pressure difference between the wing’s surfaces. The wing’s shape and angle of attack make air accelerate over the top, creating lower pressure, while air on the bottom stays higher in pressure. The higher pressure beneath pushes the wing upward, and the lower pressure above reduces downward push, producing a net upward force. Additionally, the wing deflects air downward; by Newton’s third law, this downward momentum change of the air gives the wing an upward reaction force. This is an aerodynamic effect, not gravity or propulsion, and it isn’t about capturing more air molecules on top. The lift outcome is the integrated pressure difference across the wing surfaces.