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Question
The initial state of a certain gas is (Pi, Vi, Ti). It undergoes expansion till its volume becomes Vf. Consider the following two cases:
- the expansion takes place at constant temperature.
- the expansion takes place at constant pressure.
Plot the P-V diagram for each case. In which of the two cases, is the work done by the gas more?
Solution
The situation is shown in the given P-V graph, where variation is shown for each process.
It is clear from the graph that Process 1 is isobaric and Process 2 is isothermal.
Since the work done is equal to the area under the P-V curve. Here, the area under the P-V curve 1 is more. So, work done is more when the gas expands in the isobaric process as in comparison to gas expands in isothermal.
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