A gas expands from a volume of $V_1=2{\text{ m}}^3$ to $V_2=4{\text{ m}}^3$ at a constant pressure of $P=10^5\text{ Pa}$. What is the work done by the gas in Joules?

Solution

1. The work done at constant pressure is given by $W=P\Delta V$.
2. The change in volume is $$\begin{array}{rl}\Delta V& =V_2-V_1\\ & =4{\text{ m}}^3-2{\text{ m}}^3\\ & =2{\text{ m}}^3\end{array}$$.
3. Substituting the values, $$\begin{array}{rl}W& =10^5\text{ Pa}\times 2{\text{ m}}^3\\ & =2\times 10^5\text{ J}\end{array}$$.
4. Hence the answer is (B).