Maximizing Efficiency: Uncovering the Truth About Heat Engines

AI Thread Summary
No heat engine can exceed the efficiency of a reversible engine, as demonstrated by the Carnot theorem. If a heat engine were more efficient, it could theoretically drive a reversible engine in reverse, creating perpetual motion, which violates the second law of thermodynamics. The discussion highlights confusion around the implications of this theorem, particularly regarding the transfer of heat from cold to hot reservoirs. Participants seek clarification on the theoretical underpinnings and practical implications of these concepts. Understanding these principles is crucial for grasping the limitations of heat engine efficiency.
cheez
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Show that no heat engine can be more efficient than a reversable engine.

I really don't have any idea. Can someone shows me any direction of doing it?
 
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Show it experimentally? good luck! see you in about 10 years ...

Algebraically? starting with WHAT as your given statements?

Logically? Most textbooks show that if some heat engine WAS more efficient
than a reversible one, then the reversible one run backwards hooked up to the "super-efficient" one, would do mechanical Work endlessly.
See "Carnot" in your index ...
 
I have read "the carnot engine" and "2nd law" a lot of times, but I still can't figure out how to prove it!


From the book:
"If the more efficient engine is used to drive the Carnot engine as refrigerator, the net result would be transfer of heat from the cold to the hot reservoir."

I don't understand this statement.

please help!
 
can anyone explain the statement?
urgent! please help
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
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Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
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