Question

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

Answer 1

2 a s = v² - u²
2 a * 50 =  0² - 20²
   
 a  =  - 4 m/s²