A thermodynamic process is shown in figure. The pressures and volumes corresponding to some points in the figure are P A =3 × 104 Pa , P B =8 × 104 Pa and V A =2 × 10-3 m 3, V D =5 × 10-3 m 3. In 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 process AC would be

Question

A thermodynamic process is shown in figure. The pressures and volumes corresponding to some points in the figure are P A =3 × 104 Pa , P B =8 × 104 Pa and V A =2 × 10-3 m 3, V D =5 × 10-3 m 3. In 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 process AC would be (A) 560 J (B) 800 J (C) 600 J (D) 640 J

Tardigrade Admin · Accepted Answer

Since AB is a isochoric process. So no work is done. BC is isobaric process W=PB × (VD-VA)=240 J Therefore Δ Q=600+200=800 J Using Δ Q=Δ U+Δ W ⇒ Δ U=Δ Q-Δ W=800-240=560 J

560 J

800 J

600 J

640 J

Since AB is a isochoric process. So no work is done. BC is isobaric process W=PB​×(VD​−VA​)=240J Therefore ΔQ=600+200=800J Using ΔQ=ΔU+ΔW ⇒ΔU=ΔQ−ΔW=800−240=560J

Since AB is a isochoric process. So no work
is done. BC is isobaric process
$W = P_{B} \times (V_{D} - V_{A}) = 240 J$
Therefore $Δ Q = 600 + 200 = 800 J$
Using $Δ Q = Δ U + Δ W$
$\Rightarrow Δ U = Δ Q - Δ W = 800 - 240 = 560 J$