A solid sphere of uniform density and radius applies a gravitational force of attraction equal to on a particle placed at , distance from the centre of the sphere. A spherical cavity of radius is now made in the sphere as shown in figure. The sphere with cavity now applied an gravitational force on same particle placed at . The ratio will be

a) |
1/2 |
b) |
7/ 9 |
c) |
3 |
d) |
7 |

A solid sphere of uniform density and radius applies a gravitational force of attraction equal to on a particle placed at , distance from the centre of the sphere. A spherical cavity of radius is now made in the sphere as shown in figure. The sphere with cavity now applied an gravitational force on same particle placed at . The ratio will be

a) |
1/2 |
b) |
7/ 9 |
c) |
3 |
d) |
7 |

1 Answer

127 votes

**(b)**

Gravitational force due to solid sphere,

where and are mass of the solid sphere and particle respectively and is the radius of the sphere. The gravitational force on particle due to sphere with cavity = force due to solid sphere creating cavity, assumed to be present above at that position

So,

127 votes

127