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fatcat39
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Entropy and Engines
A heat engine has the following diagram associated with it. There is a heat source which supplies 1000 J of heat energy during one cycle and remains at a constant temperature of 400 K. A heat sink exhausts 700 J of heat during a cycle at a constant temperature of 300 K. Both are reversible processes. During one cycle the engine itself doesn't change its entropy.
A) How much work can this engine do in one cycle?
B) Calculate change of entropy of heat source through one cycle?
C) Calculate change of entropy of heat sink through one cycle of engine?
D) Does this engine violate second laws of thermodynamics?
Q_{H} = Q_{L} + W
\DeltaS = Q/T
I just need someone to check my work. Thanks!
A) 1000 = 700 + W
W = 300 J
B) 1000 J/ 400 k = 3 J/K (well, 2.5, but with one sigfig...)
C) 700 J/ 300 K = 2 J/K (again, 2 and 1/3, but round down...)
D) No, because heat is lost in order to do work.
Homework Statement
A heat engine has the following diagram associated with it. There is a heat source which supplies 1000 J of heat energy during one cycle and remains at a constant temperature of 400 K. A heat sink exhausts 700 J of heat during a cycle at a constant temperature of 300 K. Both are reversible processes. During one cycle the engine itself doesn't change its entropy.
A) How much work can this engine do in one cycle?
B) Calculate change of entropy of heat source through one cycle?
C) Calculate change of entropy of heat sink through one cycle of engine?
D) Does this engine violate second laws of thermodynamics?
Homework Equations
Q_{H} = Q_{L} + W
\DeltaS = Q/T
The Attempt at a Solution
I just need someone to check my work. Thanks!
A) 1000 = 700 + W
W = 300 J
B) 1000 J/ 400 k = 3 J/K (well, 2.5, but with one sigfig...)
C) 700 J/ 300 K = 2 J/K (again, 2 and 1/3, but round down...)
D) No, because heat is lost in order to do work.
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