Question

The $P-V$ diagram of a diatomic ideal gas system going under cyclic process as shown in figure. The work done during an adiabatic process $CD$ is (use $\gamma =1.4$):

• A. $200\text{J}$
• B. $-500\text{J}$
• C. $-400\text{J}$
• D. $400\text{J}$

Answer 1

The correct option is B $-500\text{J}$

workdone for adiabatic process is
$W_{CD}=\frac{nR\Delta T}{1-\gamma }=\frac{P_f{v}_f-P_i{v}_i}{1-\gamma }=\frac{200\times 3-100\times 4}{1-1.4}$
$W_{CD}=\frac{600-400}{-0.4}=-\frac{200}{0.4}=-500\text{J}$
$W_{CD}=-500\text{J}$