The thermal insulation in a refrigerator is never perfect. Typically energy is transferred thermally from the room to the refrigerator interior at a rate of \(60 \mathrm{~W}\) with the refrigerator door closed. Suppose the interior needs to be held at \(4.0^{\circ} \mathrm{C}\) and the temperature of the room is \(20^{\circ} \mathrm{C}\). At what minimum rate must mechanical energy be delivered to the refrigerator to maintain the interior at \(4.0^{\circ} \mathrm{C}\) ?