Eight charges each of value q each are placed on a ring of radius R placed in x-y plane with origin at centre -q charge having mass m is projected from `z = oo` towards the centre of the ring with velocity v. The velocity of -q when it reaches the centre of ring is (neglect gravity)-

Options

A. `sqrt((8kq^(2))/(mR))`
B. `sqrt((8kq^(2))/(mR)+v)`
C. `sqrt((16kq^(2))/(mR)+v^(2))`
D. `sqrt((16kq^(2))/(mR)+v)`

Answer

C

Explanation

`U_(i) +K_(i) = U_(f) +K_(f)`
`0+(1)/(2) mv^(2) = (-k8q^(2))/(R) +(1)/(2)mv^(2)`
`:. v' = sqrt((16kq^(2))/(mR)+v^(2))`