A thin, high-strength steel rule (E = 30 ×106 psi) having thickness t= 0.175 in. and length L = 48 in. is bent by couples M0 into a circular are subtending a central angle α = 40° (see figure).
(a) What is the maximum bending stress σmax in the rule?
(b) By what percent does the stress increase or decrease if the central angle is increased by 10%?
