Correct Answer - A::C
Let `x` be the displacemental of ring. Then displacemental of the particle is `x_(o) - x`, or `(3.0 - x) m`.
Centre of mass will not move. Hence,
`(5.4 xx 10^(9)) x = (6 xx 10^(8)) (3 - x)`
Solving, we get
`x = 0.3 m`
Apply conservation of linear momentum and conservation of mechanical energy.