A thermodynamic process is shown in the figure. 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^(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 :

Options

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

Answer

A

Explanation

a. By the graph, `W_(AB) = 0` and `W_(BC) = 8 xx 10^(4) [5 - 2] xx 10^(-3) = 240 J`
`:. W_(AC) = W_(AB) + W_(BC) = 0 + 240 = 240 J`
Now, `Delta Q_(AC) = Delta Q_(AB) + Delta Q_(BC) = 600 + 200 = 800 J`
From the first of thermodynamics,
`Delta Q_(AC) = Delta U_(AC) + Delta W_(AC)`
`implies 800 = Delta U_(AC) + 240 implies Delta U_(AC) = 560 J`