A thermodynamic process is shown in the following figure. The pressures and volumes corresponding to some points in the figure are:
$\begin{array}{l} P_{A} = 3 \times 10^{4} Pa \\ V_{A} = 2 \times 10^{- 3} m^{3} \\ P_{B} = 8 \times 10^{4} Pa \\ V_{D} = 5 \times 10^{- 3} m^{3} \end{array}$
In the process AB, 600 J of heat is added to the system and in process BC , 200 J of heat is added to the system. The change in internal energy of the system in the process AB would be

Question

A thermodynamic process is shown in the following figure. The pressures and volumes corresponding to some points in the figure are:

$\begin{array}{l} P_{A} = 3 \times 10^{4} Pa \\ V_{A} = 2 \times 10^{- 3} m^{3} \\ P_{B} = 8 \times 10^{4} Pa \\ V_{D} = 5 \times 10^{- 3} m^{3} \end{array}$

In the process AB, 600 J of heat is added to the system and in process BC , 200 J of heat is added to the system. The change in internal energy of the system in the process AB would be

Infinity Learn · Accepted Answer

No work is done along the path AB, because the process is isochoric.∴  Work done     $$=PBVD$$−VA    $$=8$$×$$1045$$×$$10$$−$$3$$−$$2$$×$$10$$−$$3=240J$$    $$QAC=QAB+QBC=600+200=800J$$∴ $$($$Δ$$U)AC=Q$$    −$$W=800$$−$$240=560J$$

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