Answer:
it is 1 / square root of the change in distance
Explanation:
since the equation of the gravitational force is
[tex]F=G{\frac{m_1m_2}{r^2}}[/tex]
then F and r are inversely related, by the equation
[tex]F \alpha \frac{1}{r^2}[/tex]
this means when F is multiplied by 2 then r^2 is multiplied by half
so when r is multiples by half we first square the number (0.5) ^ 2 = 0.25
so
[tex]F \alpha \frac{1}{(0.25)r^2}[/tex]
which means F is multiples by 1/0.25 or 4 when the radius is halfed
