PT - Accident Investigation Lesson

Accident Investigation

Introduction

Math is used in accident investigation to determine factors of the accident such as the speed that the car was traveling. The skid marks, or tire tracks, are used to reenact the accident and determine what happened. Watch the videos and take notes on skid speed and yaw marks and how they are used to investigate an accident.

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Skid Speed

In Your Notebook: Watch the following video and take down important notes, such as formulas. Pause the video at times to attempt the practice examples on your own before viewing the solutions!

Summary:

• The length of a tire's skid mark is an indication of the speed of the vehicle. 
• The drag factor is a measure of the friction generated between a tire and the road surface.

Skid Speed Formula:

$S=\sqrt{Dfn}$

 

S = minimum speed of the vehicle

D = average length of skid marks

f = drag factor

n = braking efficiency (as a decimal)

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Yaw Marks

In Your Notebook: Watch the following video and take down important notes, such as formulas. Pause the video at times to attempt the practice examples on your own before viewing the solutions!

Summary:

• A yaw mark is a mark a tire makes when a vehicle wheel slides sideways on the surface of a road.

Yaw Mark Formula:

$S=\sqrt{15fr}$

 

S = minimum speed of the vehicle

f = drag factor

r = radius of the arc created by the yaw marks

 

To Determine the Radius of the Yaw Mark:

$r=\frac{c^2}{8M}+\frac{M}{2}$

 

C = distance of the chord

M = distance of the middle ordinance

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Accident Investigation Practice

Click through the interactive activity, or read the transcript below, to practice these new concepts. 

Click here to view the transcript of the above interactive activity. Links to an external site.

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Driving Math Practice

Test your knowledge of driving math and accident investigation with this activity.

 

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