A sample of ideal gas initially at point A on a pressure–volume (P–V) diagram has a pressure of 100 kPa and a volume of 1.0 L. The gas is taken to point B (3.0 L, 100 kPa) by an isobaric expansion and is then returned to point A along a path that lies entirely above the horizontal line P = 100 kPa.
Answer the following qualitatively; no numerical calculations are required.
(a) Describe how you would determine, from the P–V diagram, the work done BY the gas during the isobaric expansion from A to B. State the sign (positive, negative, or zero) of this work according to the convention that work done BY the gas is positive.
(b) Explain how you could decide—by examining only the diagram—whether the magnitude of the work done ON the gas during the return path from B back to A is greater than, less than, or equal to the magnitude found in part (a). Justify your answer without performing a calculation.
(c) For the entire cycle A → B → A, state whether the net work done BY the gas is positive, negative, or zero and provide a qualitative explanation based on the geometry of the diagram.