Thermodynamics Question 235
Question: A perfect gas goes from a state A to another state B by absorbing $ 8\times 10^{5}J $ of heat and doing $ 6.5\times 10^{5}J $ of external work. It is now transferred between the same two states in another process in which it absorbs $ 10^{5}J $ of heat. hi the second process
Options:
A) work done by gas is $ 10^{5}J $
B) work done on gas is $ 10^{5}J $
C) work done by gas is $ 0.5\times 10^{5}J $
D) work done on the gas is $ 0.5\times 10^{5}J $
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Answer:
Correct Answer: D
Solution:
[d] $ dU=dQ-dW=( 8\times 105-6.5\times 105 ) $
$ =1.5\times 10^{5}J $
$ dW=dQ-dU=10^{5}-1.5\times 10^{5} $
$ =-0.5\times 10^{5} $
$ - $ ve sign indicates that work done on the gas is $ 0.5\times 10^{5}J $
