Question

An auto moving at a velocity of 20m/s can have a maximum deceleration of 10m/s*2 . The driver of the auto sees a girl playing on the road at 20 m and applies the full brakes, can he avoid the accident? ​

Answer 1

Given :

initial velocity of  the auto , u = 20 m/s

maximum deceleration of the auto , a = 10 m/$s^{2}$

distance of the playing girl = 20 m

To find :

The auto driver can avoid the accident or not .

Solution :

when auto will stop , its final velocity will be zero .

final velocity , v = 0

Let the distance after which auto will stop be x .

using 3rd equation of motion ,

         $v^{2}$ = $u^{2}$ + 2 * a * x

=>      0 = 20 * 20 + 2 * ( -10 ) * x

=>  400 = 20 * x

=> x = 20 m

The distance after which auto will stop =  the distance of the playing girl , so the auto driver can avoid the accident .