A furnace of 70- by 60- by 90-cm inside dimensions is constructed of a material having a thermal conductivity of 0.5 Btu/h · ft · ◦F. The wall thickness is 6 in. The inner and outer surface...

A furnace of 70- by 60- by 90-cm inside dimensions is constructed of a material
having a thermal conductivity of 0.5 Btu/h · ft · ◦F. The wall thickness is 6 in. The
inner and outer surface temperatures are 500 and 100◦F, respectively. Calculate the
heat loss through the furnace wall.