Use a Free body diagram
Extracted text: Prob. 2.3-7. For small loads, P, the rotation of "rigid" beam AF in Fig. P2.3-7 is controlled by the stretching of rod AB. For larger loads, the beam comes into contact with the top of col- umn DE, and further resistance to rotation is shared by the rod and the column. Assume (and later show that this is a valid as- sumption) that the angle 0 through which beam AF rotates is small enough that points on the beam essentially move verti- cally, even though they actually move on circular paths about the fixed pin at C. (a) A load P is applied at end F that is just sufficient to close the 1.5-mm gap between the beam and the top of the column at D. What is the strain, e, in rod AB for this value of load P? (b) If load P is increased further until e, = 0.001 , what is the corresponding strain, e, in column DE? 3m Gap 1.5 mm 4 m (1) (2) 3 m