To compute speed from a yaw mark, which of the following is needed?

To compute speed from a yaw mark, it is necessary to take into account the coefficient of friction, the chord, and the middle ordinate. The coefficient of friction is critical as it defines the frictional force available to a vehicle as it makes a turn, which directly affects how quickly a vehicle can turn without losing traction.

The chord refers to the straight-line distance between the beginning and end points of the yaw mark, while the middle ordinate is a measurement that represents the distance from the midpoint of the chord to the arc of the yaw mark. These measurements together provide the necessary geometric parameters to calculate the curvature of the path taken by the vehicle as it turned.

Using all three components allows for a more accurate calculation of speed because it incorporates both the physical forces acting on the vehicle due to the turn and the geometry of the path taken. This understanding is essential in accident reconstruction and determining vehicle dynamics during maneuvers, especially in law enforcement scenarios.