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Unformatted text preview: ME320 Thermodynamics Homework set #6 Due: Wednesday 10/15/03 at the start of class 1. Consider a fixed mass of an ideal gas at a given temperature T 1 and pressure P 1 that is expanded quasistatically from a volume V 1 to a volume V 2 . Is the work done greater if the expansion occurs under isobaric or isothermal conditions? Solution: For the isobaric expansion, the work done is W isobaric = P 1 ( V 2- V 1 ) . Taking into account that the gas is ideal, the work done for the isother- mal expansion is W isothermal = mRT 1 ln parenleftbigg V 2 V 1 parenrightbigg = P 1 V 1 ln parenleftbigg V 2 V 1 parenrightbigg . Since, for V 2 > V 1 , V 2- V 1 > V 1 ln parenleftbigg V 2 V 1 parenrightbigg it therefore follows that W isobaric > W isothermal . Alternatively, the foregoing result can be seen by noting that, for the isothermal process, P 2 = mRT 1 V 2 < mRT 1 V 1 = P 1 , and considering the area under the process curve....
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This note was uploaded on 04/11/2008 for the course MASE 320 taught by Professor Shen during the Spring '08 term at Washington University in St. Louis.
- Spring '08