A thermodynamic process is shown in this figure. The pressure and volumes corresponding to some points in the figure are

`P_(A) = 3 xx 10^(4) Pa` `V_(A) = 2 xx 10^(3) m^(3)`
`P_(B) = 8 xx 10^(4) Pa`, `V_(D) = 5 xx 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