1. The problem statement, all variables and given/known data One surface moves over the other stationary surface. a. Is friction felt by both the surfaces? b. Is the friction force same in magnitude? c. What are the direction of friction forces felt by them? 2. Relevant equations 3. The attempt at a solution Since both the surface are in relative motion and touching each other, the friction force should be produced. But i could not imagine how the stationary surface feel the friction. This is my first attempt at physics forum. If someone can provide the clear example that lets me imagine, it will be greatly helpful.