# The initial state of a certain gas is (P1, V1, T1). It undergoes expansion till its volume becoms Vf.

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The initial state of a certain gas is (P1, V1, T1). It undergoes expansion till its volume becoms Vf. Consider the following two cases:

(a) the expansion takes place at constant temperature.

(b) 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?

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edited

The P-V digram for each case is shown in the figure.

In case (i) P1 V1 = Pf Vf ; therfore process is isothermal.

Work done = area under the PV curve

so work done is more when the gas expands at constant pressure.