Two massive, positively charged particles are initially held a fixed distance apart. When they are moved farther apart, the magnitude of their mutual gravitational force changes by a factor of n. Which of the following indicates the factor by which the magnitude of their mutual electrostatic force changes?
a. 1/n2
b. 1/n
c. n
d. n2

c. n

The magnitude of the gravitational force is given by Newton's law of universal gravitation:

Here G is the gravitational constant, are the masses of the particles and d is the distance between them.

The magnitude of the electrostatic force is given by Coulomb's law:

Here k is the Coulomb constant, are the chargues of the particles and d is the distance between them.

As can be seen, both forces are inversely proportional to the square of the distance. Thus, the factor is the same in both cases.

newton's first law of motion