The value of g at a certain height h above the free surface of the earth is x/4 where x is the value of g at the surface of the earth. The height h is
R
2R
3R
4R
x=GMR2
Again, x4=GM(R+h)2 or x=GM2R+h2
∴ 1R2=2R+h2=2R+h or R+h=2R or h=R