Thermodynamics Question 297
Question: When the state of a gas adiabatically changed from an equilibrium state A to another equilibrium state B an amount of work done on the system is 35 J. If the gas is taken from state A to B via process in which the net heat absorbed by the system is 12 cal, then the net work done by the system is $ ( 1cal=4.19J ) $
Options:
A) 13.2 J
B) 15.4 J
C) 12.6 J
D) 16.8 J
Show Answer
Answer:
Correct Answer: B
Solution:
[b] In the first-case adiabatic change, $ \Delta Q=0,\Delta W=-35J $ From 1st law of thermodynamics, $ \Delta Q=\Delta U+\Delta W, $
In the second case $ \Delta Q=12cal=12\times 4.2J=50.4J $
$ \Delta W=\Delta Q-\Delta U=50.4-35=15.4J $
