Two comets have identical masses. However, one comet is four times farther from the Sun than the other. According to Newton's Universal Law of Gravitation, the force of gravity exerted by the Sun on the more distant comet is
A) one-quarter the size of the force exerted on the closer comet
B) one-sixteenth the size of the force exerted on the closer comet
C) the same size as the force exerted on the closer comet
D) four times as large as the force exerted on the closer comet

Question

Quizplus · Accepted Answer

According to Newton's Universal Law of Gravitation, the force of gravity between two objects is directly proportional to their masses and inversely proportional to the square of the distance between them. In this case, the two comets have identical masses, but the more distant comet is four times farther from the Sun than the closer comet. Therefore, the distance between the Sun and the more distant comet is squared (4^2 = 16) times larger than the distance between the Sun and the closer comet. Using the inverse square law, we can see that the force of gravity exerted by the Sun on the more distant comet will be 1/16th (or one-sixteenth) the size of the force exerted on the closer comet. Therefore, the correct answer is B) one-sixteenth the size of the force exerted on the closer comet.

Two Comets Have Identical Masses