1.3 Determine the force P necessary for the equilibrium of a steel bar shown in Fig. 1.69. The diameters of the first, middle and the last segments of the bar are 30 mm, 25 mm and 30 mm respectively. Also, find the elongation of the bar. E = 200 GPa. (250 kN, 0.536 mm) 200 kN 100 kN 150 kN |+ 600 mm-|+800-mm|1000-mm- Fig. 1.69