where mv is the vehicle mass (in kilograms), g is the acceleration due to gravity (in meters per square second), Cr is the rolling friction coefficient, and α is the slope angle (in degrees). The rolling friction coefficient Cr depends on many variables. The most important influencing quantities are vehicle speed v, tire pressure p, and road surface conditions. For many applications, particularly when the vehicle speed remains moderate, the rolling friction coefficient Cr may be assumed to be constant.