An asteroid exerts a 360-N gravitational force on a nearby spacecraft. If the spacecraft moves to a point 3 times as far from the center of the asteroid, the force will be
A) 1080 N.
B) 360 N.
C) zero.
D) 40 N.
E) 120 N.

Question

Quizplus · Accepted Answer

The gravitational force between two objects is inversely proportional to the square of the distance between them. If the distance is tripled, the force becomes $1/3^2 = 1/9$ of the original force. Therefore, $360\, \text{N} / 9 = 40\, \text{N}$.

An Asteroid Exerts a 360-N Gravitational Force on a Nearby