What bending moment is required to produce a maximum normal stress of 400 MPa: (a) In a straight round rod of 40-mm diameter? (b) In a straight square rod, 40 mm on a side (with bending about the X...

What bending moment is required to produce a maximum normal stress of 400 MPa:

(a) In a straight round rod of 40-mm diameter?

(b) In a straight square rod, 40 mm on a side (with bending about the X axis as shown for a rectangular section in Appendix B-2)?