As we know,
F=GR2Mm
Given,
F = 10 N, when separation = R,
Hence,
F1 = R2G M m = 10 N [Equation 1]
If separation = 2R then,
Substituting the values in the formula above, we get,
F2=(2R)2G M mF2=R24G M m
F2=4×(R2G M m) [Equation 2]
Substituting the value of equation 1 in equation 2 we get,
F2 = 4 x 10 N = 40 N