Question

A gas is initially at a pressure of 100 $kPa$ and its volumeis 2$\cdot 0m^3$ . Its pressure is kept constant and the volume is changed from 2$\cdot 0m^3$ to 2$\cdot 5m^3.$ Its volume is now kept constant and the pressure is increased from 100 $kPa$ to 200 $kPa$ . The gas is brought back to its initial state, the pressure varying linearly with its volume. (a)Whether the heat is supplied to or extracted from the gas in the complete cycle? (b) How much heat was supplied or extracted?

Answer 1

a) $P_1=100KPa$

$V_1=2m^3$

$\Delta V_1=0.5m^3$

$\Delta P_1=100kpa$

From the graph, We find that area under AC is gretater than area under than $AB$. So, we see that heat is extracted from the system.

b) Amount of heat = Area under ABC

$=\frac{1}{2}\times \frac{5}{10}\times {10}^5=25000J$