A metal plate 16 cm by 8 cm is placed outside on a clear night. The plate, which has an emissivity of 0.7, exchanges heat by radiation with the night sky which is at -40 C. Air at -10 C flows over the top of the plate, cooling it with a heat transfer coefficient of 42 W/m^2 K. The plate is insulated on its underside and heated by an electric resistance heater. How much electric power must be supplied to maintain the plate at 55 C?
A metal plate 16 cm by 8 cm is placed outside on a clear night. The plate, which has an emissivity of 0.7, exchanges heat by radiation with the night sky which is at -40 C. Air at -10 C flows over the top of the plate, cooling it with a heat transfer coefficient of 42 W/m^2 K. The plate is insulated on its underside and heated by an electric resistance heater. How much electric power must be supplied to maintain the plate at 55 C?