The earth is an approximate sphere. If the interior contained matter which is not of the same density every where, then on the surface of the earth, the acceleration due to gravity

Options

A. Will be directed towards the centre but not the same everywhere
B. Will have the same value everywhere but not directed towards the centre
C. Will be same everywhere in magnitude directed towards the centre
D. Cannot be zero at any point

Answer

D

Explanation

If we assume the earth as a sphere of uniform density, then it can be treated as point mass placed at its centre. In this case acceleration due to gravity , g=0 at the centre. It is not so, if the earth is considered as a sphere of non-uniform density, in that case value of g will be different at different points and cannot be zero at any point.