problem20_55

University Physics with Modern Physics with Mastering Physics (11th Edition)

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20.55: a) Consider an infinitesimal heat flow H dQ that occurs when the temperature of the hot reservoir is : T | | | | ) / ( H H C C H C C H C C S T T dQ T Q T dQ T dQ dQ T T dQ C = = - = - = b) The 1.00 kg of water (the high-temperature reservoir) goes from 373 K to 273 K. J. 10 6.2 J 10 4.19 J 10 57 . 3 Then J 10 57 . 3 so engine, the of out comes J 10 57 . 3 ) K J 1308 )( K 273 ( | | gives (a) part of result The J/K 1308 ) 373 273 ln( ) K kg J 4190 )( kg 00 . 1 ( ) ( ln S J 10 19 . 4 ) K 100 )( K kg J 4190 )( kg 00 . 1 ( 4 5 5 H C 5 C C 5 C 1 2 5 H × = × + × - = + = × - = × = = - = = = × = = = Q Q W Q Q Q T T mc T mc Q h c) 2.00 kg of water goes from 323 K to 273 K J 10 4 . 3 J 10 85 . 3 | | K J 10 41 . 1 ) 323 / 273 ( ln ) K kg J 4190 )( kg 00 . 2 ( ) ( ln J 10 19 . 4 ) K 50 )( K kg J 4190 )( kg 00 . 2 (
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Unformatted text preview: 4 H C 5 h C C 3 1 2 5 H = + = -= -= -= = = = = = Q Q W S T Q T T mc S T mc Q h d) More work can be extracted from 1.00 kg of water at 373 K than from 2.00 kg of water at 323 K even though the energy that comes out of the water as it cools to 273 K is the same in both cases. The energy in the 323 K water is less available for conversion into mechanical work....
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This document was uploaded on 02/06/2008.

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