Question

A thermodynamic process is carried out from an original state D to an intermediate state E by the linear process shown in figure.
The total work is done by the gas from D to E to F is

• A. 100 J
• B. 800 J
• C. 300 J
• D. 250 J

Answer 1

Answer: (B)

Total work done by the gas from D to E to F is equal to the area of DDEF.
∴ The area of DDEF = $\frac{1}{2}$ DF $\times$ EF
Here, DF = change in pressure = 600 - 200
$\quad\quad$$\quad\quad$$\quad\quad$$\quad\quad$$\quad\quad$$\quad\quad$= 400 N m^-2
Also, EF = change in volume = 7 m³ - 3 m³
$\quad\quad$$\quad\quad$$\quad\quad$$\quad\quad$$\quad\quad$$\quad\quad$= 4 m³
Area of DDEF $=\frac{1}{2}\times400\times4=800$ J
Thus, the total work done by the gas from D to E to F is 800 J.