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Unformatted text preview: 7B MT1 Saturday Review Problems Patrick Varilly * 21 Feb 2008 1 Liphardt, Spring 05, Prob 2 In an experiment liquid helium at an initial temperature of 1.0 K is to be cooled further by bringing it into contact with a solid which is initially at a lower temperature T . The heat capacity of the liquid helium may be expressed as c L = aT 3 where a = 0 . 128 J K- 4 , and the heat capacity of the solid may be expressed as c S = bT- 2 where b = 0 . 015 J K. Assume the mixture to be mechanically and thermally isolated from the rest of the universe and no work is done in the process. a) How much heat must leave the liquid helium to cool it from 1.0 K to 0.7 K? b) What must be the initial temperature of the solid, T , if the final temperature of the system, helium (initially at T = 1 . 0 K) plus solid (initially at T = T ), is to be 0.5 K? c) Find the total change in the entropy of the universe during this process. To minimize the chance of math errors, leave this answer in terms of the parameters a and b . 2 Smoot, Fall 06, Prob 4a-c For a modern power plant, the pressure of the steam can be as high as 70 atmospheres at 300 C (573 K); the exhaust is at one atmosphere and perhaps 40 C (313 K). * Thanks to Steve Byrnes for typing up several of these problems and their solutions 1 7B MT1 Saturday Review Session Problems Patrick Varilly a) For such a power plant, what is the maximum thermodynamic efficiency?...
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This note was uploaded on 06/30/2010 for the course PHYSICS ?? taught by Professor Zettle during the Spring '08 term at University of California, Berkeley.
- Spring '08