Question

The gravitational intensity at the centre of a hemispherical shell of uniform mass density has the direction indicated by the arrow (see the following figure).

1. a,

2. b,

3. c,

4. 0

Answer 1

Correct answer is (3) c.

The gravitational intensity at any point is defined as the negative of the potential gradient i.e.,(-dv/dx)

At any point inside the spherical shell, the value of gravitational potential is constant implying the intensity is zero.

So, intensity at all points inside is zero. Since the upper half is cut *** there is no attractive force on the upper portion to pull if upwards. So effectively the net force is downwards along c.