A 10-ft-long hollow steel tube is lifted by a crane as shown in Figure 2.1. The tube has a square cross section (see the top view in the figure). The

tube and two identical cables are connected at A and B by a pin of diameter d (= 8 in) (see the side view in the figure). The inner and outer dimensions of the tube cross section are b = 8 in and b2 = 10 in. Note that the density of the steel tube is 490 lb/ft³. a) Determine the minimum diameter of the pin when the allowable shear stress in the pin is10,000 psi and the allowable bearing stress between the pin and the tube is 12,000 psi. b) Determine the normal stress at cross-section a---a in the figure when the location of a---a is L/2 from the base (the lowest point) of the tube.