ABSTRACT
When two bodies are placed in contact and then caused to move relative to each other, we nd that a force is required to maintain a constant velocity. This is contrary to our ideas of equilibrium: we expect that, once set in motion, the bodies will continue to move with respect to each other at a constant velocity. To preserve this idea, a new force concept, called the frictional resultant or restraining force, was created. As we will see, this force results from interactions between the bodies.
