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)` towards `B`. Particle `B` starts moving away from `A` with constant acceleration of `2 m s^(-1)`.
The time for which there is a minimum distance between the two is .

Options

A. `20 m`
B. `15 m`
C. `25 m`
D. `30 m`

Answer

b

Explanation

Distance travelled by `A` in time `5`, s `S_(1) =10 xx 5=50 m`
Distance travelled by `B` in time `5 s`
`S_(2) =(1)/(2) at^(2) =(1)/(2) xx 2 xx 5^(2) =25 m`
Mimnimum distance `=40 +S^(2) -S_(1) =15 m`.