A bar with a circular cross-sectional area is made of SAE 1045 carbon steel having a yield stress of σY = 150 ksi. If the bar is subjected to a torque of 30 kip . in. and a bending moment of 56 kip . in., determine the required diameter of the bar according to the maximum-distortion-energy theory. Use a factor of safety of 2 with respect to yielding.