Engineering Board Exam Reviewer · Thermodynamics · hard
Air at 500 kPa and 1 m3 expands isentropically in a closed system to 100 kPa. What is the work done by the air? (k = 1.4)
- 804.7 kJ
- 400.0 kJ
- 645.1 kJ
- 460.8 kJ
Answer
D. 460.8 kJ
Solution
V2 = 51/1.4 = 3.157 m3. W = (P1V1 - P2V2)/(k - 1) = (500 - 315.7)/0.4 = 460.8 kJ.
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