The Physics
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Opus in profectus

Engines

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Practice

practice problem 1

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solution

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practice problem 2

0.40 moles of an ideal, monatomic gas runs through a four step cycle. All processes are either adiabatic or isochoric. The pressure and volume of the gas at the extreme points in the cycle are given in the first two data rows of the table below.
  1. Sketch the PV graph of this cycle.
  2. Determine the temperature at state A, B, C, and D.
  3. Calculate W, Q, and ΔU on the path A→B, B→C, C→D, D→A and for one complete cycle. (Include the algebraic sign with each value.)
A four step cycle (adiabatic & isochoric)
state A B C D  
P (Pa) 100,000 1,462,000 5,850,000 400,000  
V (m3) 0.010 0.002 0.002 0.010  
T (K)  
path A→B B→C C→D D→A ABCDA
description adiabatic isochoric adiabatic isochoric closed cycle
ΔU (J)  
Q (J)  
W (J)  
  1. Determine the…
    1. real efficiency
    2. ideal efficiency (Carnot efficiency)
    … of a heat engine running this cycle.

solution

  1. Answer
  2. Answer
  3. Answer it
A four step cycle (adiabatic & isochoric)
state A B C D  
P (Pa) 100,000 1,462,000 5,850,000 400,000  
V (m3) 0.010 0.002 0.002 0.010  
T (K) 300 880 3,520 1,200  
path A→B B→C C→D D→A ABCDA
description adiabatic isochoric adiabatic isochoric closed cycle
ΔU (J) +2,890 +13,160 −11,550 −4,500 0
Q (J) 0 +13,160 0 −4,500 +8,660
W (J) +2,890 0 −11,550 0 −8,660
  1. Answer
    1. it
    2. it

practice problem 3

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solution

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practice problem 4

Write something completely different.

solution

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