PProb. 3.4-6. A uniform rod of diameter d is subjected to axial loads at the three cross sections, as illustrated in Fig. P3.4-6. If the displacement at the right end, up, cannot ex- ceed 5 mm, and the maximum axial stress in the rod cannot exceed 80 MPa, what is the minimum allowable diameter of the (circular) cylindrical rod? Use E = 70 GPa. uc up d A (1) B (2) C (3) D 2.5 m 80 kN 100 kN 3.0 m P3.4-6 60 kN 3.5 m