Question

A car is travelling at a speed of 20m/s.A child runs onto the road 50 metres ahead.The driver applies brakes, WHAT SHOULDBE THE DECCELERATION FOR THE CAR TO STOPJUST BEFORE THE CHILD

Answer 1

by equation of motion v^2-u^2=2as
here final velocity is 0 as car is stopped
initial velocity is 20 m/s
putting in eqn 0-20^2=2a50
-400=100a
-400/100=a
-4m/s^2 is required deceleration