Question

Given the graph below which shows the pressure and volume of a gas as it goes through cyclic process ABCA, how much work is done by the gas as it goes through this process?

• A. $-1200J$
• B. $-800J$
• C. $600J$
• D. $800J$
• E. $1200J$

Answer 1

Answer: (D)

$800J$

Area enclosed by the closed path under PV graph gives the work done by the gas in a cyclic process.

From figure, $AC=4\times {10}^5$ Pa $BC=4\times {10}^{-3}$ $m^3$

Thus work done during cyclic process $W=$ Area of triangle(ACB)

$\therefore$ $W=\frac{1}{2}\times AC\times BC=\frac{1}{2}\times 4\times {10}^5\times 4\times {10}^{-3}=+800$ J