An ideal parallel-plate capacitor with air between its plates has an initial capacitance \(C_0\). The capacitor is charged by a battery to a potential difference \(V_0\), storing an initial electrostatic energy \(U_0\), and is then disconnected from the battery. The surface area of each plate is subsequently doubled while the separation distance between the plates is simultaneously tripled. What are the new capacitance \(C\) and the new energy \(U\) stored in the capacitor in terms of \(C_0\) and \(U_0\)?