A shell of mass M and radius R has point mass m placed at a distance r from its centre. The gravitational potential energy U(r) vs r will be

Options

A.
B.
C.
D.

Answer

D

Explanation

The gravitational potential energy U (r ) has a constant value inside the shell for `r le R`.
and it is given by `U (r ) = -(GMm)/(r )`
For `r gr R, U (r )=-(GMm)/(r )`
It decreases as r increases.