Lift and Newton’s Third Law

Newton’s third law identifies that for every force there is an equal and opposite reacting force. In addition to Bernoulli’s principle, Newton’s third law can also be used to explain the lift being created by a wing. As the air travels around a wing and leaves the trailing edge, the air is forced to move in a downward direction. Since a force is required to make something change direction, there must be an equal and opposite reacting force. In this case, the reacting force is what we call lift. In order to calculate lift based on Newton’s third law, Newton’s second law and the formula “Force = Mass × Acceleration" would be used. The mass would be the weight of air flowing over the wing every second, and the acceleration would be the change in velocity the wing imparts to the air.

The lift on the wing as described by Bernoulli’s principle, and lift on the wing as described by Newton’s third law, are not separate or independent of each other. They are just two different ways to describe the same thing, namely the lift on a wing.

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