Two positively charged particles ` X` and `Y` are initially far away from each other and at rest , `X` begins to move towards `Y` with some initial velocity. The total momentum and energy of the system are `p` and `E`.

Options

A. If `Y` is fixed both `P` and `E` are conserved
B. If `Y` is fixed ,`E` is conserved but not `P`.
C. if both are free to move `p` is conserved but not `E`.
D. if both are free,`E` is conserved but not `p`

Answer

B

Explanation

`(A) v_(A)-V_(B)`=work done by electric field on `+1` coul.charge form `A` to `B` =`Erq`
`:.v_(B)=V_(A)-E Rq=v-E Rq`