A large massive rock is in contact with the Earth. Draw a force diagram for the rock and the Earth. Which of the following statements is true?
A) The gravitational force on the rock due to the Earth and the gravitational force on the Earth due to the rock are interaction partners.
B) The gravitational force on the rock due to the Earth and the contact force on the Earth due to the rock are interaction partners.
C) The contact force on the Earth due to the rock and the gravitational force on the Earth due to the rock are interaction partners.
D) The gravitational force on the Earth due to the rock and the contact force on the Earth due to the rock are interaction partners.

Question

Quizplus · Accepted Answer

According to Newton's third law, every action has an equal and opposite reaction. The gravitational force on the rock due to the Earth and the gravitational force on the Earth due to the rock are equal in magnitude and opposite in direction, and therefore they are interaction partners. The contact force on the Earth due to the rock is not an action-reaction pair with the gravitational force, as it is a separate force that arises from the contact between the two objects.

A Large Massive Rock Is in Contact with the Earth