Question

If the moon were twice as far from earth how much weaker would earth pull on moon be

Answer 1

Gravitational pull is inversely proportional to square of the distance b/w two objects.

That is :

$\sf G = \frac{m_1m_2}{r^2}$

If u increase the r to 2r, then G would be,

$\sf G = \frac{m_1m_2}{(2r)^2} => \frac{m_1m_2}{4r^2}$

Hence, the pull will be 4 times weaker.