If you drop your textbook, it falls because the earth pulls it downward. At the same time, your textbook pulls on the earth with a force that is
A) equal to the downward pull on the textbook and in the same direction.
B) equal to the downward pull on the textbook but in the opposite direction.
C) immeasurably small.
D) zero.

Question

Quizplus · Accepted Answer

According to Newton's third law, for every action, there is an equal and opposite reaction. Therefore, when the textbook pulls on the earth, the earth pulls back on the textbook with an equal force, but in the opposite direction. This force is called the gravitational force and it acts between any two objects with mass. Therefore, the correct choice is B, where the force between the earth and the textbook is equal and opposite.

If You Drop Your Textbook, It Falls Because the Earth