physics
posted by emma on .
The speed limit in a school zone is 38 km/h. A driver traveling at this speed sees a child run onto the road 16 m ahead of his car. He applies the brakes, and the car decelerates at a uniform rate of 8.5 m/s2. If the driver's reaction time is 0.55 s, What is the stopping distance of the vehicle?

X = Stopping distance
= (reaction time)*Vo + Vo^2/(2a)
The second term of that sum is the distance travelled while decelerating.
Make sure Vo is in m/s.
38 km/h = 10.56 m/s
X = 5.51 m + 6.56 = 12.07 m