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University of Nebraska–Lincoln

Transportation Systems Engineering

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Lesson Overview
Lesson Title:
Vehicle Stopping Distance

Mr. Nicholas Reding (Primary)

Brief Description:
This is a lesson that requires students to gather data from observing street traffic and then calculate speed of vehicles. They then predict stopping distance at certain speeds with certain road conditions.

Topics Introduced:
Position, Time, Speed, Velocity, Friction, Stopping Distance

Transportation, Distribution, and Logistics Curriculum Framework Components Addressed:
Transportation Operations
Health, Safety and Environmental Management
Suggested Grade Levels:
10th Grade
11th Grade
12th Grade

Standards Taught:
12.1.3 Science 2003
12.3.4 Science 2003
12.7.5 Science 2003

Lesson Information
Learning Expectations:

Students will learn a simple way to calculate the average speed of a moving vehicle by measuring distance traveled and time of travel. Students will also learn about the relationship between initial speed, coefficient of friction, and stopping distance for vehicles. A connection between physics and driving safety can be made.

Plan Of Action:

Begin by asking students why we have speed limit signs posted on our roads and why they vary from place to place. Also discuss the precautions that drivers must take when road conditions are worsened by rain or snow. Next, introduce the idea that a net force is needed to bring a moving vehicle to a stop. That force usually comes from friction between the tires and the road. At this time hand out the labs and begin the activity. Students will predict stopping distances for different speeds and different coefficients of friction and then go outside to collect some traffic data. The traffic data will be the average speed for vehicles. If desired, a radar gun can also be used to find the average speed of cars as a comparison to the mathematical calculation the students will do. Then the lab will guide students through the stopping distance formula and include the information about the importance of the coefficient of friction. Finally, the students will calculate the percent difference between the stopping distance at two different speeds and then the stopping distance for the same speed but with different road conditions.

Data Set Used:

Students will collect data of vehicle speed by measuring time and displacement and then calculating speed. Data (initial speeds and different coefficients of friction) will be provided for calculating stopping distances.

Materials Needed:

Materials needed include the lab handout, pen/pencil, calculator, measuring tape or measuring wheel, timers, access to safe viewing of traffic, and a radar gun (optional).

Preparation Period:

The only preparation needed is to find a safe viewing area with two reference points where students can observe traffic. If a radar gun is going to be used as a reference to the student calculations of speed (optional) then arrangements need to be made to obtain a radar gun.

Implementation Period:

This activity will take one or two classes (50 min each). It really depends on how long the students gather traffic speeds. The rest of the lab does not require data collection and can be done in one class period.

Science, Math, Engineering and / or Technology Implications:

Students will hopefully see the connection between physics and the motion of vehicles (their own cars or semi-trucks used for transportation). Vehicles require different stopping distances depending on initial speed and the friction between the road and tires which may change depending on the weather. Simple algebra is also used.

Unexpected Results:

After doing this lab with my Honors Physics classes, I was surprised at how much fun they had using the radar gun. I had to make sure that students took turns using the radar to make sure we had enough time to give everyone a chance. This data collection with the radar gun took longer than I expected. A class of about 25 students took almost an entire 50 minute class period to collect data (including taking attendance, handing out lab, giving quick directions, and time to walk from classroom to street and back into classroom again.)

Considerations for Diversity in Education:

This lab combines a hands on approach by gathering data outside as well as applying math to the concepts of speed and force.

Lesson Files
Stopping Distance Lecture
A short PowerPoint in PDF format for an introduction to the lab.
[size: 977623] [date uploaded: Nov 06, 2009, 2:33 pm ]

Stopping Distance Lab
The student lab handout in PDF format for the stopping distance lab.
[size: 36616] [date uploaded: Nov 06, 2009, 2:34 pm ]

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