Question $5$

A solid circular shaft with diameter $D$ is subjected to a bending moment of $30$ kNm $,$ and the permissible bending stress is not to exceed $15M\frac{N}{m^2}.$ Find the diameter of the shaft.

$I=\frac{D^4}{64}$ for a solid circular shaft $$

Question $6$

A uniform rectangular cross$-$sectional horizontal beam of length $4$ m and depth $150$ mm rests on supports at its ends and supports a concentrated load of $10$ kN at its mid$-$point. Determine the maximum tensile and compressive stresses in the beam if it has a second moment of area of $2\mathrm{.}8{10}^{-5}{m}^4.$ Assume the weight of the beam is negligible.