$7\mathrm{.}85$ The $38-$mm$-$diameter shaft $AB$ is made of a grade of steel for which the yield strength is ${}_Y=250$MPa. Using the maximum$-$shearingstress criterion, determine the magnitude of the torque $T$ for which yield occurs when $P=240kN.$

Fig. P$7\mathrm{.}85$

$7\mathrm{.}86$ Solve Prob. $7\mathrm{.}85,$ using the maximum$-$distortion$-$energy criterion.

SOLVE QUESTION $7\mathrm{.}86$