Suppose a car is traveling at +23.7 m/s, and the driver sees a traffic light turn red. After 0.427 s has elapsed (the reaction time), the driver applies the brakes, and the car decelerates at 9.00 m/s2. What is the stopping distance of the car, as measured from the point where the driver first notices the red light?

Answer 1

For the reaction time,
distance = velocity * time
= 23.7*0.427
= 10.12 m

For the braking time,
v²-u^sup2;=2aS
v=0, u=23.7 m/s, a=-9 m/s^2,
S=(v²-u^sup2;)/(2a)
=-23.7^sup2/(2*(-9))
=32.21 m

Stopping distance is the sum of the two distances.