The device serves as a compact torsional spring. It is made of A$-36$ steel and consists of a

solid inner shaft $CB$ which is surrounded by and attached to a tube $AB$ using a rigid ring at $B.$

The ring at A can also be assumed rigid and is fixed from rotating. If a torque of $T=2$kip$-$in is

applied to the shaft, determine $($a$)$ the angle of twist at the end $C$ and the maximum shear stress

in $($b$)$ the tube and $($c$)$ the shaft.

Use $G=11$ Msi