Question

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

Answer 1

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

In case (i) P₁ V₁ = P_f V_f ; therfore process is isothermal. 

Work done = area under the PV curve 

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