Two cars `C_(1) & C_(2)` are moving in parallel lanes in the same direction at speeds `90kph & 108kph` respectively (see figure). As the traffic signal turns red, both applies brake (assume constant retardation) simultaneously. If they both stop together at the dead line

Options

A. distance of dead line from `C_(2)` is `300m`
B. destance of dead line from `C_(1)` is `250m`
C. time taken by the cars to ends up after the signal turn red is `15sec`.
D. time taken by the cars to ends up after the signal turn red is `20sec`.

Answer

`A, B, D`

Explanation

(i) Relative initial velocity `=5 m//s`, relative final velocity `=0`
Relative displacement `=50m`
Relative acceleration `=` constant
`rArr 50=((5+0)/(2))t rArr txx20sec.`
(ii) Distance of dead line from car `C_(1)=((25+0)/(2))xx20=250m`.