1. Each of the four struts shown to the left Po = 7.5 kN Po P consists of a solid steel rod of length of 900 mm and Young's modulus of E = 200 GPa. Po The axial compressive force is Po = 7.5 kN. (a) If the diameter of rod (1) is 20 mm, determine the factor of safety with respect to buckling. (b) Determine the required diameter for each of the rods (2) - (4) if the 900 mm factor of safety must be the same as for rod (1). Ans: (a) FS = 2.55; (b) d2 = 28.3 mm, d3 = 14.14 mm, d4 = 16.73 mm. (1) (2) (3) (4)