Question $5$

Show that the maximum bending stress for a beam of rectangular cross$-$section is ${}_{\text{m}\text{a}\text{x}}=(M\frac{c}{\text{I}}),[\frac{2n+1}{3n}],$ if$,$ instead of Hooke's law, the stress$-$strain relationship is ${}^n=E,$ where $n$ is a number dependent on the properties of the material.