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Unformatted text preview: Homework 1 Solutions Spring 2010 Required Problems Chapter 17 8. When the concrete cools in the winter, it will contract, and there will be no danger of buckling. Thus the low temperature in the winter is not a factor in the design of the highway. But when the concrete warms in the summer, it will expand. A crack must be left between the slabs equal to the increase in length of the concrete as it heats from 15 o C to 50 o C. ( 29 ( 29 ( 29 6 3 12 10 C 12 m 50 C 15 C 5.0 10 m T a-- D = D = ´ ° °- ° = ´ ll 50. The ideal gas law can be used to relate the volume at the surface to the submerged volume of the bubble. We assume the amount of gas in the bubble doesn’t change as it rises. The pressure at the submerged location is found from Eq. 13-6b. submerged submerged surface surface surface submerged submerged surface atm surface surface submerged submerged surface submerged atm submerged constant P V PV P V PV nRT nR T T T P T P gh T V V V P T P T ρ = → = = → = → + = = ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 5 3 3 2 3 5 3 1.013 10 1.00 10 kg m 9.80m s 37.0m 273.15 18.5 K 1.00cm 1.013 10 Pa 273.15 5.5 K 4.79cm ´ + ´ + = ´ + = é ù ë û 71. ( a )The iron floats in the mercury because Hg Fe ρ ρ . As the substances are heated, the density of both substances will decrease due to volume expansion. The density of the mercury decreases more upon heating than the density of the iron, because...
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