The 150-mm-thick wall of a gas-fired furnace is constructed of fireclay brick (k = 1.5 w/m k, = 2600 kg/m3, cp = 1000 j/kg k) and is well insulated at its outer surface. the wall is at a uniform initial temperature of 20°c, when the burners are fired and the inner surface is exposed to products of combustion for which t[infinity] = 950°c and h = 100 w/m2 k. (a) how long does it take for the outer surface of the wall to reach a temperature of 750°c? (b) plot the temperature distribution in the wall at the foregoing time, as well as at several intermediate times.