A jet airplane flies at a constant velocity through the air. Its jet engines exert a constant force forward on the plane that exactly balances the force of air friction exerted backward on the plane. These forces are equal in magnitude and opposite in direction. Do we know this because of Newton's second law or Newton's third law?
A) Newton's second law
B) Newton's third law
C) Both laws
D) Neither (explain)

Question

Quizplus · Accepted Answer

Newton's second law explains that the net force on an object is equal to the mass of the object multiplied by its acceleration. Since the airplane is flying at a constant velocity, the net force is zero, indicating that the forward force from the engines is equal and opposite to the backward force of air friction. Newton's third law, on the other hand, deals with action-reaction pairs between two different objects, which is not the case here.

A Jet Airplane Flies at a Constant Velocity Through the Air