Problem 3: Using a standard square cross-section with A = b and Io = A/12 as reference a) Compute the bending shape factor QB for a thin-wall circular cross section with 40 mm outer radius and 36 mm inner radius. 40mm 36mm b) Calculate the cross-sectional area of a solid square cross-section with the same value of cross-sectional moment of inertia as the thin-wall circular tube in part (a). c) Determine the relative weights of two beams with equal length L, one with the thin-wall circular cross section and the other with the solid square cross section. Both beams are constructed from the same material. d) Calculate the shape factor for a hollow square cross section with b/t=5. e) Calculate the shape factor for an I-beam with h/b = 3, t/b = 0.125. f) Which of the cross-sections in parts (d) and (e) will provide the lightest weight beam if the beam material used is the same? Why? t b H