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Part A In this problem you will estimate the heat lost by a typical house, assuming that the temperature inside s Tin = 20"C and the temperature outside is How much heat per second H (= Q/AT) is lost from the house due to heat conduction? Tout = 0"C. The walls and uppermost ceiling of a typical house are supported by 2 x 6-inch wooden Give your answer in watts, rounding to the nearest 10 W. beams (Kwood = 0.12 W/(mk )) with fiberglass View Available Hint(s) insulation (kins = 0.04 W/(mK)) in between. The true depth of the beams is actually 5.625 inches, but we will take the thickness of the walls and ceiling to be Lwall = 18 cm to allow for the JAI interior and exterior covering. Assume that the house is a cube of length _ = 9.0 m on a side. Assume that the roof has very high conductivity, so H W that the air in the attic is at the same temperature as the outside air. Ignore heat loss through the ground. The effective thermal conductivity of the Submit wall (or ceiling) koff, is the area-weighted average of the thermal conductivityes of the wooden beams and the fiberglass insulation that make up each of them. Allowing for the fact that the 2 x 6 beams Part B are actually only 1.625 inches wide and are spaced 16 inches center to center, a calculation of this conductivity for the walls yields keff = 0.048 W/(mK). For simplicity, assume Let us assume that the winter consists of 150 days in which the outside temperature is 0" C. This will give the that the ceiling also has the same value of koff. typical number of "heating degree days" observed in a winter along the northeastern US seaboard. (The cumulative number of heating degree days is given daily by the National Weather Service and is used by oil companies to determine when they should fill the tanks of their customers.) Given that a gallon (3.4 kg) of oil liberates Q = 1.4 x 108 J when burned, how much oil will be needed to supply the heat lost by conduction from this house over a winter? Assume that the heating system is 75% efficient. Give your answer numerically in gallons to two significant figures. View Available Hint(s) AED Gallons consumed = 27.8 gallons per winter Submit Previous Answers * Incorrect; Try Again; 9 attempts remaining Provide Feedback Next >