An isolated solid conducting sphere of radius \(R\) initially carries a net positive charge \(Q_0\) and possesses electrostatic potential energy \(U_0\). A second uncharged solid conducting sphere of radius \(3R\) is placed a very large distance away. The two spheres are then connected by a long, thin conducting wire until electrostatic equilibrium is established. What are the final charge \(Q_2\) on the sphere of radius \(3R\) and the total final electrostatic potential energy \(U_f\) stored in the two-sphere system?