Algebra.Com's Answer #682219 by ikleyn(52786)![\"\"](\"/images/stars/stars-13.gif\")  
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document.write( "A tank of water has been outdoors in cold weather until a 6.00 cm thick slab of ice has formed on its surface.
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document.write( "The air above the ice is at -17.0 degrees C. Calculate the rate of formation of ice (in centimeters/hour) on the bottom surface
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document.write( " of the ice slab. Take the thermal conductivity of ice to be 0.0040 cal/s-cm-degree C, the density to be 0.92 g/cm^3,
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document.write( "and the heat of fusion to be 80 cal/g. Assume that no heat enters or leaves the water through the walls of the tank.
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document.write( "The units are not SI, but they all are consistent (!), so we can make all calculations from the beginning to the end
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document.write( "without making conversion the units (thanks to God).\r
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document.write( "1. The general balance equation is \r\n" );
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document.write( "  =  .\r\n" );
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document.write( " The right side is the heat flow by conductivity from the water in the tank to the atmosphere through the ice layer: \r\n" );
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document.write( " DELTA(T) is the temperature difference of 17 °C across the ice layer; \r\n" );
document.write( " (we assume that the water temperature in the tank is 0 °C under the ice layer)\r\n" );
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document.write( " L = 6 cm is the layer thickness;\r\n" );
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document.write( "  = 0.004  is the thermal conductivity of ice.\r\n" );
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document.write( " The left side is the amount of heat to increase the thickness of the ice layer:\r\n" );
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document.write( "  is the rate of the thickness increasing, in  ; it is the value and the quantity under the problem question;\r\n" );
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document.write( "  is the specific latent heat of freezing, 80  ;\r\n" );
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document.write( "  is the density of ice, 0.92  .\r\n" );
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document.write( " You may check that the dimensions of both sides are consistent.\r\n" );
document.write( " If you never did/check it before, make this very useful exercise. \r\n" );
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document.write( "2. Now substitute all given data to get\r\n" );
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document.write( " =  = 0.000154 = 0.554  .\r\n" );
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document.write( "Answer. The rate of formation of ice is 0.554 under the given condition.\r
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