Question

A gas within a closed chamber undergoes the cyclic process as shown in the $p-V$ diagram. The horizontal scale is set by $V_s=4.0{\text{m}}^3$. Calculate the net energy added to/released by the system as heat during one complete cycle.

• A. $60\text{J}$
• B. $25\text{J}$
• C. $30\text{J}$
• D. $45\text{J}$

Answer 1

The correct option is C $30\text{J}$

We know that in a cyclic process,
Change in internal energy $\left(\Delta U\right)=0$
Thus,
Work done by/on system $=$ Heat added/released $=$ Area under $P-V$ graph
$\Rightarrow \Delta Q=-\frac{1}{2}\times (4-1)\times (30-10)=-30\text{J}$
$[$anticlockwise$]$
This means that $30\text{J}$ of heat energy has been released by the system.