Question

A thermodynamic system undergoes a cyclic process as shown in figure. Over one complete cycle, work done by the system is .............. .

• A. $0$
• B. $>0$
• C. $<0$
• D. Nothing can be said

Answer 1

The correct option is B $>0$

Work done by a gas is given by $W=\int PdV$
With basic calculus we see that for a closed (cyclic) loop, a clock wise path gives positive work = Area of the loop. An anti clockwise loop gives negative work, whose magnitude is the area of the loop.
Here we have one positive loop and one negative. The positive loop has a larger area than the negative loop. Hence the net work for the cycle is positive.