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Unformatted text preview: Homework 2 Feb. 1, 2007 2. a. efficiency = w q 1 = 0 . 75 q 1 = 133 . 3 kJ Also, efficiency = 1 + q 3 q 1 = 0 . 75 q 3 = 33 . 3 kJ The negative sign of w means the system does work on surroundings. The positive sign of q 1 means heat enters into the system from the hotter heat reservoir. Finally, the negative sign of q 3 means heat enters into the colder heat reservoir from the system. b. The system operates in reverse. Thus, q 1 = 133 . 3 kJ and q 3 = 33 . 3 kJ. The positive sign of w means the work is done to the system. The negative sign of q 1 means heat enters into the hotter heat reservoir from the system. Finally, the positive sign of q 3 means heat enters into the system from the colder heat reservoir. c. The same calculation as in part a but different values for efficiency. q 1 = 125 kJ and q 3 = 25 kJ. d. From part b and c, ( q 1 + q 1 ) = 8 . 3 kJ and ( q 3 + q 3 ) = 8 . 3 kJ The negative sign of ( q 1 + q 1 ) means that heat enters into the hotter heat reservoir from the system. The positive sign of ( q 3 +...
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This note was uploaded on 08/03/2009 for the course BME 100 taught by Professor Yuan during the Spring '07 term at Duke.
 Spring '07
 YUAN

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