The gravitational intensity at the centre of a hemispherical shell of uniform mass density has the direction indicated by the arrow: 

1. a, d
2. b, d
3. c, e
4. d, e

A rocket is fired from the earth towards the sun. At what distance from the earth’s centre is the gravitational force on the rocket zero?

Given, the mass of the sun = $2\times {10}^{30}$ kg, the mass of the earth =  $6\times {10}^{24}$kg, and orbital radius = $1.5\times {10}^{11}$ m. Neglect the effect of other planets etc.
1. 2.59 × 10⁸ m
2. 3.10 × 10⁸ m
3. 4.07 × 10⁸ m
4. 2.23 × 10⁸ m