A certain circular shaft is subjected to a maximum equivalent bending moment of $36,000$ in $-$ lb and a

maximum equivalent torque of $42,000$ in $-$ lb $.$ The allowable unit stresses are $12,000$ psi for bending and

$8000$ p si for shear. Expressed as a multiple of $\frac{1}{4}$ in$.,$ the required diameter of the shaft is

A$.\frac{31}{2}$ in

B$.3\frac{3}{4}$ in$.$

C$.3\frac{1}{4}$ in

D$.3$ in$.$

You answered: D

Found in : Mechanics Of Materials, Part $3,$

Torsion in Members

The formula for the allowable average compressive unit stress in a long steel column is given as

$F_c=\frac{149,000,000}{(\frac{Kl}{r}{)}^2}$

A column consists of a $W1240$ with an unsupported length of $24$ ft and end conditions for which $K=1\mathrm{.}0.$

The area of the section is $11\mathrm{.}8$ sq $.$ in$.,$ and its least moment of inertia is $44\mathrm{.}1in.{?}^4$ The maximum axial load that

can be carried safely by the column is

A$.78,400lb.$

B$.80,100lb.$

C$.79,200lb.$

D$.78,000lb.$