1. The problem statement, all variables and given/known data A uniform ladder rests against a vertical wall where there is negligible friction. The bottom of the ladder rests on rough ground where there is friction. The top of the ladder is at a height h above the ground and the foot of the ladder is at a distance 2a from the wall. The diagram shows the forces that act on the ladder. Which equation is formed by taking moments? (A) Wa + Fh = 2Wa (B) Fa + Wa = F h (C) Wa + 2Wa = Fh (D) Wa – 2Wa = 2Fh 2. Relevant equations moment=F x perpendicular distance 3. The attempt at a solution Should the answer be (C)? The anticlockwise moments are Wa and 2Wa and the clockwise moment is Fh, so they should be equated. But which is the pivot? Is the pivot one of the ends of the ladder or some other point on the ladder. Shouldn't the forces have to be split into components because the force and distance must be perpendicular to each other. And shouldn't the distance be taken along the length of the ladder and not the ground?