Two blocks of metal, each of mass \(10 \mathrm{~kg}\) and a specific heat of \(0.4 \mathrm{~kJ} / \mathrm{kg} \mathrm{K}\), are at a temperature of \(40^{\circ} \mathrm{C}\). A reversible refrigerator receives heat from one block and rejects heat to the other. Calculate the work required to cause a temperature difference of \(100^{\circ} \mathrm{C}\) between the two blocks.