Thermodynamics Question 267
Question: In a thermodynamic process, pressure of a fixed mass of gas is changed in such a manner that the gas molecules gives out 30 joules of heat and 10 J of work is done on the gas. If the initial internal energy of the gas was 40 J, then final internal energy will be
Options:
A) zero
B) 80 J
C) 20 J
D) -20 J
Show Answer
Answer:
Correct Answer: C
Solution:
[c] Given that $ dQ=-30J $ and$ ~dW=-10J $
$ E _{i}=40J $ and let final internal energy$ =E _{f} $ So, $ dQ=E _{f}-E _{i}+dW $
$ -30=E _{f}-40-10 $
$ E _{f}=20J $
