A 1-in.-thick steel plate measuring 10 in. in diameter is heated from below by a hot plate, its upper surface exposed to air at 80°F. The heat-transfer coefficient on the upper surface is 5 Btu/h ft °F and k for steel is 25 Btu/h ft °F.
a. How much heat must be supplied to the lower surface of the steel if its upper surface remains at 160°F? (Include radiation.)
b. What are the relative amounts of energy dissipated from the upper surface of the steel by convection and radiation?