1. The problem statement, all variables and given/known data Three building materials, plasterboard [k = 0.30 J/(s m Co)], brick [k = 0.60 J/(s m Co)], and wood [k = 0.10 J/(s m Co)], are sandwiched together (as I've tried to show below). The temperatures at the inside and outside surfaces are 28.9°C and 0°C, respectively. Each material has the same thickness and cross-sectional area. Find the temperature (a) at the plasterboard-brick interface and (b) at the brick-wood interface. Outside (0 C) --- Wood | Brick | Plasterboard --- Inside (28.9 C) 2. Relevant equations (Q/t)=(kAΔT)/L 3. The attempt at a solution I was able to solve for the correct temperatures of 21°C and 18°C for the plaster-brick and brick-wood interfaces, respectively; however, this solution was based on the assumption that the rate of heat transfer would be the same for all three materials. This seemed proper at the time. As I think about it in retrospect, however, wouldn't the rates of heat transfer differ among the materials due to their differing conductivity (k)? As in, certain materials are more "receptive" of heat and will transfer it more readily -- how can that be, if all three rates are assumed to be the same? EDIT: I may have mixed up my terminology. The fact that heat itself (Q) is the same across all three materials -- that makes more sense to me than the rates being the same (as I figure t would differ). The same amount of heat will progress from one end to another, if I've understood correctly. How is the heat received differently by the materials -- as in, do any of the materials absorb some of the heat, preventing it from being transferred onward to the next interface? I'm just confusing myself more and more! If someone could straighten out this issue for me, I would deeply appreciate it! Thank you!