Question

A driver applies the brakes on seeing traffic signal 400m ahead. At the time of applying of brakes vehicle was moving with speed `15 m//s`. The brakes provide uniform deceleration of `0.3m//s^(2)`. The displacement of the vehicle in 1min duration after the driver sees the signal is :
A. `25m`
B. `375m`
C. `360m`
D. `40m`

Answer 1

The maximum distance covered by the vehicle before coming to rest `=(v^(2))/(2a)=((15)^(2))/(2(0.3))=375m`
The corresponding time `(t)=(v)/(a)=(15)/(0.3)=50s`. Therefore after `50 seconds`, the distance covered by the vehicle `=375m` from the instant of application of the brakes.
`rArr` The distance of the vehicle from the traffic light after one minute `=(400-375)m=25m`