Two point masses m and M are separated by a distance d. If the distance between the masses is increased to 3d, how does the gravitational force between them change?
A)The force will be one-third as great.
B)The force will be one-ninth as great.
C)The force will be three times as great.
D)The force will be nine times as great.
E)It is impossible to determine without knowing the numerical values of m, M, and d.

Question

Quizplus · Accepted Answer

The gravitational force between two masses is inversely proportional to the square of the distance between them. When the distance between the masses is increased from d to 3d, the new distance is nine times the original distance. Therefore, the new force will be (1/9)^2 = 1/81 times the original force, which is equivalent to saying that the force will be one-ninth as great.

Two Point Masses M and M Are Separated by a Distance