Two particles `P` and `Q` simulaneously start moving from point `A` with velocities `15m//s` and `20m//s` respectively. The two particles move with acceleration equal in magnitude but opposite in direction. When `P` overtakes `Q` at `B` then its velocity is `30m//s`. Find velocity of `Q` at point `B` ( in m/s).

Options

A. `30 ms^(-1)`
B. `5 ms^(-1)`
C. `20 ms^(-1)`
D. `15 ms^(-1)`

Answer

B

Explanation

For `P, 30=15+at` or `at=15ms^(-1)`
For `Q, upsilon = 20 -at` or `upsilon = 20-15=5 ms^(-1)`