<P> There are several ways to explain how an airfoil generates lift . Some are more complicated or more mathematically rigorous than others; some have been shown to be incorrect . For example, there are explanations based directly on Newton's laws of motion and explanations based on Bernoulli's principle . Either can be used to explain lift . </P> <P> An airfoil generates lift by exerting a downward force on the air as it flows past . According to Newton's third law, the air must exert an equal and opposite (upward) force on the airfoil, which is the lift . </P> <P> The air flow changes direction as it passes the airfoil and follows a path that is curved downward . According to Newton's second law, this change in flow direction requires a downward force applied to the air by the airfoil . Then, according to Newton's third law, the air must exert an upward force on the airfoil . The overall result is that a reaction force, the lift, is generated opposite to the directional change . In the case of an airplane wing, the wing exerts a downward force on the air and the air exerts an upward force on the wing . </P> <P> The downward turning of the flow is not produced solely by the lower surface of the airfoil, and the air flow above the airfoil accounts for much of the downward - turning action . </P>

How does a plane wing create lift which physics concept applies