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phy131studiof15:lectures:finalp1sol [2015/12/02 09:34]
mdawber [Question 5]
phy131studiof15:lectures:finalp1sol [2015/12/02 09:36]
mdawber [Question 6]
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 ===== Question 6 ===== ===== Question 6 =====
  
-A. $e=\frac{W}{Q_{H}}$+{{phy141f12finalq8fig.png}} 
 + 
 +The diagram shows the P-V diagram for a 40\% efficient ideal Carnot engine. Assume the gas used in this Carnot engine is an ideal diatomic gas. 
 + 
 +A. (5 points) For every Joule of work obtained from the engine, how much heat needs to be added to engine? 
 + 
 +$e=\frac{W}{Q_{H}}$
  
 $Q_{H}=\frac{1}{0.4}=2.5\mathrm{J}$ $Q_{H}=\frac{1}{0.4}=2.5\mathrm{J}$
  
-B.$Q_{H}=W+Q_{L}$+B. (b) (5 points) For every Joule of work obtained from the engine how much heat is lost to the environment?​ 
 + 
 +$Q_{H}=W+Q_{L}$
  
 $Q_{L}=1.5\mathrm{J}$ $Q_{L}=1.5\mathrm{J}$
  
-C. $P_{B}V_{B}=nRT_{H}$+C. (5 points) At points B and D the gas in the system has the same volume, but different temperatures. If the gas at point D is at twice atmospheric pressure, what is the pressure of the gas at point B? 
 + 
 +$P_{B}V_{B}=nRT_{H}$
  
 $P_{D}V_{D}=nRT_{L}$ $P_{D}V_{D}=nRT_{L}$
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 $P_{B}=3.33P_{atm}$ $P_{B}=3.33P_{atm}$
  
-D. The expansion from B to C is adiabatic so $P_{B}V_{B}^{\gamma}=P_{C}V_{C}^{\gamma}$+D. (5 points) If the volume of the gas at point B is 1L what is the volume of the gas at point C? 
 + 
 +The expansion from B to C is adiabatic so $P_{B}V_{B}^{\gamma}=P_{C}V_{C}^{\gamma}$
  
 For a diatomic gas $\gamma=\frac{7}{5}$ For a diatomic gas $\gamma=\frac{7}{5}$
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 $V_{C}=3.6\mathrm{L}$ $V_{C}=3.6\mathrm{L}$
  
-E. $\Delta S=0\mathrm{\frac{J}{K}}$+E. (5 points) How much does the net entropy of the engine and the environment change for every Joule of work done by this Carnot engine? 
 + 
 + 
 +$\Delta S=0\mathrm{\frac{J}{K}}$
phy131studiof15/lectures/finalp1sol.txt · Last modified: 2015/12/02 09:36 by mdawber
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