Static friction, sliding friction and rolling friction

To begin, the experiment P1.2.6.1 verifies that the static friction force F_H and the sliding friction force F_G are independent of the size of the contact surface and proportional to the resting force G on the base surface of the friction block. Thus, the following applies:

The coefficients µ_H and µ_G depend on the material of the friction surfaces. The following relationship always applies:

To distinguish between sliding and rolling friction, the friction block is placed on top of multiple stand rods laid parallel to each other. The rolling friction force F_R is measured as the force which maintains the friction block in a uniform motion on the rolling rods. The sliding friction force F_G is measured once more for comparison, whereby this time the friction block is pulled over the stand rods as a fixed base (direction of pull = direction of rod axes). This experiment confirms the relationship: