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,
$\Delta U_{abc}+\Delta U_{ca}=0\Delta U_{abc}=-\Delta U_{ca}=180J$
$ΔQ=ΔW+ΔU$
$250+60=ΔW+180$
$ΔW=130J$