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


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