(a)
The change in entropy of the universe for each cycle.
(a)
Answer to Problem 77PQ
The change in entropy of the universe for each cycle is
Explanation of Solution
Write the expression to calculate the change in entropy of the hot reservoir.
Here,
Write the expression to calculate the change in entropy of the hot reservoir.
Here,
Write the expression to calculate the heat added to the cold reservoir.
Here, W is the work done by the engine.
Substitute the above equation in (II) to rewrite.
Write the expression to calculate the entropy change in universe.
Here,
Substitute the equation (I) and (III) in the above equation to rewrite.
Conclusion:
Substitute
Therefore, the change in entropy of the universe for each cycle is
(b)
The required more work has to be done by the Carnot engine.
(b)
Answer to Problem 77PQ
The required more work has to be done by the Carnot engine is
Explanation of Solution
Write the expression to calculate the work done by the Carnot engine.
Here,
Write the expression to calculate the efficiency of the engine.
Rewrite the equation for W using the above expression.
Write the expression to calculate the more work required.
Here,
Conclusion:
Substitute
Substitute
Therefore, the required more work has to be done by the Carnot engine is
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Chapter 22 Solutions
Physics for Scientists and Engineers: Foundations and Connections
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