A hollow circular tube A fits over the end of a solid circular bar B, as shown in the figure. The far ends of both bars are fixed. A hole through bar B makes an angle β (in radians) with a line through two holes in tube A. Bar B is twisted until the holes are aligned, and then a pin is placed through the holes. When the system returns to static equilibrium, what is the total strain energy of the two bars? (Let Ipa and Ipb represent the polar moments of inertia of bars A and B, respectively. The shear modulus of elasticity G is the same for both bars.)
