Engineering Board Exam Reviewer · Thermodynamics · hard
A gas at 100 kPa and 1 m3 is compressed polytropically (n = 1.3) to 0.5 m3. What is the work done on the gas?
- 69.31 kJ
- 77.05 kJ
- 23.11 kJ
- 100.16 kJ
Answer
B. 77.05 kJ
Solution
P2 = P1(V1/V2)n = 100(2)1.3 = 246.23 kPa. W = (P2V2 - P1V1)/(1 - n) = (123.11 - 100)/(-0.3) = -77.05 kJ, i.e., 77.05 kJ done on the gas.
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