A car is travelling at 20 m/s along a road A child runs out into the road 50 m ahead and the driver steps on the break pedal What must be the cars deceleration be if the car stops just before it reaches the chid

Answer 1

the average speed during deceleration will be 10 m/s

it takes 5 seconds to travel 50 meters at that average speed, so

1/2 at^2 = 50
a = 100/25 = 4 m/s^2