Answer to Question #14823 in Mechanics | Relativity for kari
Joe and Bill are playing tug-o-war. Joe is pulling with a force of 200 N. Bill is simply hanging on, but skidding towards Joe at a constant velocity. What is the force of friction between Bill's feet and the ground?
Only unbalanced forces cause acceleration. Since Bill is not accelerating, the 200N force must be exactly balanced by friction. Thus the friction between Bill's feet and the ground is 200N.