Question

If two objects are moved closer together so that the distance between them is one-third the original distance, what is the gravitational force after the objects are moved?
one-ninth the original gravitational force
one-third the original gravitational force
three times the original gravitational force
nine times the original gravitational force

Answer 1

Nine times the original gravitational force

Answer 2

Answer:
nine times the original gravitational force
Explanation:
The rule of the gravitational force between two bodies is shown in the attached images.
The parameters in the rule are:
Fg : the gravitational force between the two bodies
G : universal gravitational constant
m1 and m2 : the masses of the two bodies
r : the distance between the two bodies

From the given rule, we can notice that:
The force of attraction between the two bodies is inversely proportional to the square of the distance between them.
This means that:
As the distance decreases to 1/3 its original value, the gravitational force would increase by a factor of 9. 

Hope this helps :)