Consider a surface that absorbs 800W/m2 of radiant energy. The surface is surrounded by a medium at 20C with a convection coefficient of 12W/(m2K). a) Calculate the surface temperature assuming that re-radiation from the surface is zero and the surface only loses heat by convection. b) Calculate the surface temperature assuming that the surface has an emissivity of 0.8 and radiates to surroundings at 20C, as well as losing heat by convection