The College at Brockport: State University of New York
Digital Commons @Brockport
Lesson Plans
CMST Institute
1-1-2006
Safe Braking Distance using Stella
Steve Colafubo
The College at Brockport
Follow this and additional works at: http://digitalcommons.brockport.edu/cmst_lessonplans
Part of the Physical Sciences and Mathematics Commons
Recommended Citation
Colafubo, Steve, "Safe Braking Distance using Stella" (2006). Lesson Plans. Paper 297.
http://digitalcommons.brockport.edu/cmst_lessonplans/297
This Lesson Plan is brought to you for free and open access by the CMST Institute at Digital Commons @Brockport. It has been accepted for inclusion
in Lesson Plans by an authorized administrator of Digital Commons @Brockport. For more information, please contact [email protected].
Safe Braking
Distance
By: Mr. Colabufo’s Math Comp class
Problem
 We wanted to know how to drive safer by
investigating safe braking distances.
Evaluating Skid Marks
 We learned how fast a car traveled from
the length of a skid mark. We used the
formula √27x to tell us how fast a car
was going when it stopped and left a skid
on dry land.
Evaluating Skid Marks
Evaluating Skid Marks
 We found that a car left a 60 ft skid mark
if he traveled 40mph, and 120 ft skid
mark at 57 mph on dry land.
 On wet land we found that a car left a 60
ft skid mark at 28 mph, and a 120 ft skid
mark at 40 mph.
Evaluating Skid Marks
 Wet road we used:
Total Braking Distances
 We used Stella to determine total braking
distances by adding reaction time and
braking time to figure out the whole
distance. We used the formula
dr=22/15vt. We used 1 for t to stop in 1
second. And the formula db=1/20v2. Then
we added the two formulas together in
Stella.
Total Braking Distances
Total Braking Distances
 We determined that at 50 mph you would
need 537 feet to stop. This includes 132
feet of reaction time, and 405 feet of
stopping time.
Maximum Speed
 We used the following formula to help us
determine the maximum speed a car
should follow another car given the space
between the cars.
Maximum Speed
 For all graphs we used the following table
of values:
Maximum Speed
Analysis
 We found out that people drive too fast
for their safety and the safety of others.
We now understand why the speed limits
are set where they are and even feel that
they are to high, especially since most
people go at least 5 mph faster than
posted! We hope that people will slow
down knowing this information!
Maximum Speed
 We determined that with about 10 car
lengths or 150 feet between cars you can
safely drive about 48 mph, and with
about 3 car lengths or 45 feet you should
drive about 22 mph