Education Technology

• ##### Device
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition
• TI-84 Plus C Silver Edition
• TI-84 Plus CE Family
• ##### Software

TI Connect™
TI Connect™ CE

# Science: Forensics Case 13 - Life in the Fast Lane: Using skid marks to determine vehicle speed

by Texas Instruments

#### Overview

Students determine the coefficient of friction between a vehicle and a road surface. They use the length of the skidding distance to determine the speed of a vehicle before its brakes were applied. Students convert between SI units and Imperial units and rearrange equations to solve for different variables.

#### Key Steps

• Simulating a skidding car, students pull a non-rolling toy car with a dual-range force sensor at a constant velocity. From the mean of the data, students can calculate the coefficient of friction between the tires and the road. The length of the skid can be used to calculate the speed of the vehicle that was involved in the hit-and-run accident.

• Ability to convert units and rearrange equations is necessary for this activity.  Students explore the relationship between speed and stopping distance.  Using formulas in lists helps students be able to see the trends and patterns.