Probs. $9-91/92$

The internal loadings on a cross section through the $150-$mm$-$diameter drive shaft of a turbine consist of an axial force of of $12\mathrm{.}5$kN$,$ a bending moment of $1\mathrm{.}2$kNm$,$ and a torsional moment of $2\mathrm{.}25$kNm$.$ Determine the principal stresses at point A$.$ Also compute the maximum in$-$place shear stress at this point.