What is required to accurately measure a yaw mark?

To accurately measure a yaw mark, it is essential to use the chord and the middle ordinate in the first one third of the yaw mark. This method provides specific geometric measurements that are crucial for calculating the trajectory of the vehicle during the skid or yaw event.

The chord represents the straight line distance between the two endpoints of the yaw mark, while the middle ordinate is a perpendicular segment drawn from the midpoint of the chord to the arc of the yaw mark. By measuring these components in the initial portion of the yaw mark, investigators can derive accurate calculations related to the dynamics and physics at play during the crash. These measurements facilitate the reconstruction of the crash, leading to better understanding of the vehicle's movement and behavior during the event.

Other options do not provide the specific and relevant geometric tools necessary for this analysis. For instance, measuring the skid length and turn angle may offer some insight into the vehicle's motion, but it lacks the precision required to reconstruct the specific path taken during the yaw. Similarly, information about tire mark width or vehicle length and landmarks may be important in certain aspects of an investigation but do not directly contribute to the measurement of yaw marks as effectively as the chord and middle ordinate do.