Q. 653.6( 10 Votes )

A car is travelling at 20 m/s along a road. A child runs out into the road 50 m ahead and the car driver steps on the brake pedal. What must the car’s deceleration be if the car is to stop just before it reaches the child?

Answer :


U = 20m/s

s = 50 m

V = o m/s

formula used:

using, Third equation of motion

v- u2=2×a×s

On applying the formula, we get

0-(20)2=2 × a × 50

-400 =100× a

a= -4 m/s2

The car has to decelerate at a rate of 4 m/s2

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