What is necessary to calculate speed from a vehicle's yaw marks?

To calculate speed from a vehicle's yaw marks, it is essential to understand the role of various factors involved in the formula used for determining speed during a skid. The combination of the coefficient of friction, the chord, and the middle ordinate is crucial in making this calculation.

The coefficient of friction is a measure of how much grip the tires have on the road surface, which directly influences how fast a vehicle can travel before losing traction. The chord refers to the straight line connecting the endpoints of the yaw marks and helps provide a geometric understanding of how far the vehicle traveled during the skid. The middle ordinate is the distance from the chord to the arc of the skid marks at its midpoint, offering insight into the curvature of the vehicle's path as it was in motion.

Together, these three elements provide a comprehensive framework for accurately calculating the speed of the vehicle at the point where it began to lose control, allowing for a precise reconstruction of the event. The formula that incorporates these factors allows investigators to analyze the dynamics of the skid and assess the vehicle's speed leading up to the incident. Each component is essential; without one, the calculation of speed could be flawed or incomplete.