Question

An ideal gas undergoes the cyclic process $\text{abca}$ as shown in the figure. The internal energy change of the gas along the path $\text{c}\text{a}$ is $-180\text{J}$ . The gas absorb $250\text{J}$ of heat along the path $\text{a}\text{b}$ and also absorbs $60\text{J}$ of heat along the path $\text{bc}$ . Find the work done by the gas along the path $\text{a}\text{b}\text{c}$

• A. $130\text{J}$
• B. $140\text{J}$
• C. $120\text{J}$
• D. $100\text{J}$

Answer 1

Answer: (A)

Change in internal energy for a cyclic process is zero. Thus,
$\Delta U_{abc}+\Delta U_{ca}=0\Delta U_{abc}=-\Delta U_{ca}=180J$
$\Delta Q=\Delta W+\Delta U$
$250+60=\Delta W+180$
$\Delta W=130J$