A composite plane wall consists of a 5-in.-thick layer of insulation (ks = 0.029 Btu/hft°R) and a 0.75-in.-thick layer of siding (ks = 0.058 Btu/hft°R). The inner temperature of the insulation is 67°F. The outer temperature of the siding is -8°F.
Determine at steady state:
the temperature at the interface of the two layers, in °F,
