1. The problem statement, all variables and given/known data Given the following diagram: When examining the FBD for member AB how does one determine the direction of friction at B? If surfaces B and C exhibit friction. 2. Relevant equations N/A 3. The attempt at a solution I know that impending motion for post BC is in the direction of P so friction acts opposite but I am unsure as to how one determines the impending motion for Member AB. The answer provided is that the friction for member AB at surface B acts horizontally in the same direction as P.