Which law is identified as the secondary source of lift?

The identification of Newton's third law as the secondary source of lift is based on the principle that for every action, there is an equal and opposite reaction. In the context of flight, when the wings of an aircraft are designed to move through the air, they deflect air downward. As a result of this downward action, the wing experiences an upward reaction force, which contributes to the lift that allows the aircraft to rise into the air.

While Bernoulli's Principle is widely recognized as the primary explanation for lift, particularly regarding the shape and airflow over an airfoil, Newton's laws, specifically the third one, help reinforce the understanding of how lift is generated. The interplay between the changes in air pressure over the wing and the reaction force from the deflected air illustrates how both principles work together in creating lift.

In this case, the emphasis on Newton's third law highlights the fundamental physics behind the generation of lift, providing essential insight into how aircraft are able to fly when considering both lift generation methods.