posted by stoic-rider77 .
A 5.1-kg bowling ball and a 8.4-kg bowling ball rest on a rack 0.50 m apart.
(a) What is the force of gravity exerted on each of the balls by the other ball?
(b) At what separation is the force of gravity between the balls equal to 2.0e-9 N?
(a) The forces are equal and opposite in direction.
F = G*M1*M2/R^2
It's Newton's law of gravity. Learn it. Look up the constant G and solve for F.
(b) let F = 2.0*10^-9 N in the equation above and solve for separation R.