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In this problem you will estimate the heat lost by a typical house: assuming that the temperature inside is 2'3\" = 20C and the temperature outside is TDu = 0"C. The walls and uppermost ceiling oi a typical house are supported by 2 X {'rinch wooden beams [kwmd = 0.12 W;'{mK]] with berglass insulation (kinE = 0.04 WmKD 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 Lwa = 18 cm to allowforthe interior and exterior covering. Assume that the house is a cube of length L = 9.0 D] on a side. Assume that the roof has very high conductivity, so 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 wall (or ceiling) keg, is the areaweighted average of the thermal conductivities of the wood en beams and the berglass insulation that make up each of them. Allowing for the fact that the 2 X 6 beams are actually only 1.525 inches wide and are spaced 16 inches center to center, a calculation of this conductivity for the walls yields kc\" = 0. 048 WmK). For simplicity, assume thatthe ceiling also has the same value of kegs. V PartA How much heat per second H (= Qy'T) is lost from the house due to heat conduction? Give your answer in watts, rounding to the nearest 10 W. b IIv'iewrtltvailable Hint(s} V PartB Let us assume that the winter consists of150 days in which the outside temperature is 0C. This will give the 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 ll the tanks of their customers.) Given that a gallon {3.4 kg) of oil liberates Q: = 1.4 X 108 .1 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 T5% ef'cient. Give your answer numerically in gallons to two signicant gures. b llv'iewilltvailable Hint(s} Mme-=2 Gallons consumed = gallons per winter Provide Feedback Next >