The mass of the earth is `81` times the mass of the Moon and the distance between the earth and the Moon is `60` time the, radius of the earth. If `R` is the radius of the earth, then the distance between the Moon and the point on the in joining the Moon and the earth where the gravitational force becomes zero is

Options

A. `30R`
B. `15R`
C. `6R`
D. `5R`

Answer

C

Explanation

The required distance is
`x xx d/(sqrt((m_(2))/(m_(2))+1))=(60R)/sqrt(81/1+1)=6R`