A driver takes 0.20 s to apply the brakes after he sees a need for it. This is called the reaction time of the driver. If he is driving a car at a speed of 54 km/h and the brakes cause a deceleration of 6.0 m/s2, find the distance travelled by the car after he sees the need to put the brakes on.
Here speed of the car=54 km/hr=15 m/s
Distance travelled while applying brake, d=s×t=15×0.2=3 m
Here, Initial velocity, u=15 m/s
Final velocity, v=0 m/s
Acceleration, a=-6m/s2
We know distance, s is
,
Hence total distance=d+s=3+18.75=21.75 m