ABSTRACT
The methods of solution of problems where bodies are in static equilibrium under the action of any system of coplanar forces have been described. However, it has already been mentioned that when presented with practical situations, the first, and possibly most difficult, step is to draw the appropriate free-body diagram. It is important to realize that the frictional force on a body always opposes the motion of that body or the tendency for motion relative to the body in contact. The corner of the truss is supported differently; it can be seen that it is both pinned and resting on rollers which would present no resistance to motion of the truss in the horizontal direction at that point. This means there can be no horizontal component of the reaction at the support. In other words, the force exerted by the fixture on the truss must be vertical, as shown in Fig.
