A small point of mass m is placed at a distance 2 R from the centre ' O ' of a big uniform solid sphere of mass M and radius R. The gravitational…

A small point of mass $\displaystyle m$ is placed at a distance $\displaystyle 2 R$ from the centre ' $\displaystyle O$ ' of a big uniform solid sphere of mass M and radius R . The gravitational force on ' m ' due to M is $\displaystyle \mathrm{F}_1$. A spherical part of radius $\displaystyle \mathrm{R} / 3$ is removed from the big sphere as shown in the figure and the gravitational force on m due to remaining part of M is found to be $\displaystyle \mathrm{F}_2$. The value of ratio $\displaystyle \mathrm{F}_1: \mathrm{F}_2$ is