A small body is at a distance `r` from the centre of the mercury, where `r` is greater than the radius of the mercury. The energy required to shift the body from `r` to `2r` measured from the centre is `E`. The energy required to shift it form `2r` to `3r` will be

Options

A. `E`
B. `E/2`
C. `E/3`
D. `E/4`

Answer

C

Explanation

`E=U_(2)-U_(1)`
`rArr -(GMm)/(2R)+(GMm)/R=(GMm)/(2R)`
`E^(1)=-(GMm)/(3R)+(GMm)/(2R)=(GMm)/(6R)`