A rod has a circular cross section with a diameter of $2$ in $.$ It is subjected to a torque of $12$kip$*in.$ and a bending moment $M.$ The greater principal stress at the point of maximum flexural stress is $15$ ksi $.$ Determine the magnitude of the bending moment.

#$8$

The steel pipe has an inner diameter of $2\mathrm{.}75$ in $.$ and an outer diameter of $3$ in $.$ If it is fixed at $C$ and subjected to the horizontal $20-lb$ force acting on the handle of the pipe wrench, determine the principal stresses in the pipe at point $A,$ which is located on the surface of the pipe.