A uniform spherical shell gradually shrinks maintaining its shape. The gravitational poential at the centre

Question

A uniform spherical shell gradually shrinks maintaining its shape. The gravitational potential at the centre

(a) increases

(b) decreases

(c) remains constant

(d) oscillates.

Answer 1

(b) Decreases

EXPLANATION: 

The gravitational potential at the center = -GM/a.

When it shrinks 'a' decreases, the numerical value of GM/a increases but this quantity is negative hence increase in numerical value decreases the quantity.