A thermodynamic process is shown in Fig. The pressures and volumes corresponding to some points in the figure are : `P_(A) = 3 xx 10^(4) Pa, P_(B) = 8 xx 10^(4) Pa` and `V_(A) = 2 xx 10^(-3) m^(3) , V_(D) = 5 xx 10^(-3) m`.
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 energy of the process `AC` would be.

Options

A. 560 J
B. 800 J
C. 600 J
D. 640 J

Answer

A

Explanation

By adjoining graph `W_(AB)=0 and W_(BC)=8 xx 10^(4) [5-2] xx 10^(-3)=240J`
`therefore W_(ABC)=W_(AB)+W_(BC)=0+240=240J`
No,w `triangleQ_(ABC)=triangleQ_(AB)+triangleQ_(BC)=600+200=800J`
From plot, `triangleQ_(ABC)=triangleU_(ABC)+triangleW_(ABC)`
`rArr 800=triangleU_(ABC)+240`
`rArr triangleU_(ABC)=560 J=triangleU_(AC)" as U is a state function"`