Two particles `A` and `B` are initially `40 m` apart, `A` is behind `B`. Particle `A` is moving with uniform velocity of `10 m s^(-1)` toward `B`. Particle `B` starts moving away from `A` with constant acceleration of `2 m s^(-1)`.
The time which there is a minimum distance between the two is .

Options

A. `2 s`
B. `4 s`
C. `5 s`
D. `6 s`

Answer

C

Explanation

Distance between the particles will be minimum when velocity of `B` becomes equal to that of `A` , i.e. `10 m s^(-1)`.
Apply `v=u +at rArr 10 =0 + 2 t rArr t=5 s`.