Hi Question from an M2 paper (June 2009): A uniform rod AB, of length 1.5 m and mass 3 kg, is smoothly hinged to a vertical wall at A. The rod is held in equilibrium in a horizontal position by a light strut CD as shown in Figure 1. The rod and the strut lie in the same vertical plane, which is perpendicular to the wall. The end C of the strut is freely jointed to the wall at a point 0.5 m vertically below A. The end D is freely joined to the rod so that AD is 0.5 m. (a) Find the thrust in CD. (b) Find the magnitude and direction of the force exerted on the rod AB at A. Please forgive my stupidity on this but I am wondering why there is no reaction at the wall at C; is the phrasing of "freely jointed" the reason? I have to admit I'm missing this and can neither convince myself nor a student as to why this is not considered and, hence, why we do not consider any thrust acting into the wall. Any help?