An object of weight W is in free-fall close to the surface of Earth. What is the force that the object exerts on Earth?
A) a force greater than W
B) a force less than W
C) a force equal to W
D) no force at all
E) cannot be determined without additional information

Question

Quizplus · Accepted Answer

According to Newton's third law of motion, every action has an equal and opposite reaction. So, when the object is falling towards the surface of the Earth, it exerts a force (equal in magnitude and opposite in direction) on the Earth. This force is also known as the weight of the object, which is equal to W. Hence, the correct answer is C) a force equal to W.

An Object of Weight W Is in Free-Fall Close to the Surface