5-63. 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 the angle of twist at the end C and the maximum shear stress in the tube and shaft.