This document provides formulas to calculate reaction distance and braking distance. Reaction distance is the distance traveled during the driver's reaction time to brake and can be estimated with d=1.1xr, where d is distance in feet and r is speed in mph. Braking distance is the distance needed to fully stop after braking and can be estimated with b=r^2/30xF, where b is braking distance in feet, r is speed in mph, F is the driving surface factor, and examples are provided to demonstrate the calculations.

1. Objective: Calculate reaction and braking distance

2. Reaction Distance: distance a car travels during the time it takes a driver to brake the car.
You can use the following formula to estimate reaction distance.
d = 1.1 x r
d = reaction distance in feet
r = speed in mi/hr
Example 1: Dan is driving at 50 miles per hour on a dry asphalt road.
Estimate the reaction distance.

3. Braking Distance: the distance traveled by a car after the driver brakes and until the car stops completely. You can use the following
formula to estimate braking distance.
b= r x r
30 x F
b = braking distance in feet
F = driving surface factor
Example 2: Use the table to estimate Dan's braking distance from Example 1 to the nearest foot.
Type of
Surface
Asphalt
Concrete
Gravel
Packed
Snow
Driving Surface Factor
Dry Road
Wet Road
0.85
0.65
0.90
0.60
0.65
0.65
0.45
0.45

4. Worksheet pg. 241 #1-23 all