Q. A driver applies the brakes on seeing traffic signal 400 m ahead. At the time of applying the brakes vehicle was moving with 15 ms^{-1} and retarding with 0.3 ms^{-2}. The distance of vehicle after 1 min from the traffic light:

(A) 25 m

(B) 375 m

(C) 360 m

(D) 40 m

**Solution : **The maximum distance covered by the vehicle before coming to rest

s = v^{2}/2a

= (15)^{2}/2×0.3

= 375 m

The corresponding time = t = v/a

= 15/0.3 = 50 sec

Therefore after 50 seconds, the distance covered by the vehicle = 375 m from the instant of beginning of braking.

The distance of the vehicle from the traffic after one minute = (400 – 375) m = 25 m

Ans: (A)