Question No$\mathrm{.}13$: Derive an expression $EI\frac{d^{2}y}{d{x}^2}=M$ with usual notation.

Question No$\mathrm{.}14$: A high strength steel band saw, $20mm$ wide by $0\mathrm{.}8mm$ thick runs over a pulley $600mm$ in diameter. What maximum flexural stresses is developed? What minimum diameter pulley can be used without exceeding a flexural stress of $400$MPa $?$ Take $E=200$GPa