Understanding Internal Energy: Path Dependence and Point Functions

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SUMMARY

The internal energy U is a point function that uniquely depends on the initial and final states of a system, not on the path taken between them. The discussion clarifies that changes in internal energy can be measured, but the absolute value of internal energy cannot be determined. The assertion in the referenced book stating that "U depends upon path" is incorrect, as it contradicts the fundamental principles of thermodynamics.

PREREQUISITES
  • Understanding of thermodynamic concepts, specifically internal energy
  • Familiarity with state functions and path functions in thermodynamics
  • Basic knowledge of the first law of thermodynamics
  • Experience with measuring changes in thermodynamic properties
NEXT STEPS
  • Study the principles of thermodynamic state functions and their properties
  • Learn about the first law of thermodynamics and its implications on internal energy
  • Research the differences between point functions and path functions in thermodynamics
  • Examine common misconceptions in thermodynamic textbooks and their corrections
USEFUL FOR

Students preparing for engineering entrance exams, GRE Physics candidates, and anyone seeking to deepen their understanding of thermodynamic principles.

Amith2006
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Sir,
I have a doubt. The internal energy U is a unique function of any state because change in U ___________. I think the answer is internal energy U is a unique function of any state because change in U does not depend upon path.U is a point function. But the given in book is " U depends upon path". Please clear this doubt.
 
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You're absolutely right.

The change in the internal energy depends only on the inital and final states and does not depend on the path.

Also, the internal energy isn't even a unique function of the state properties. We can never measure the absolute internal energy of a state. We can only measure the changes in internal energy. So the question is doubly wrong.

What book are you using? I'm suprised that there is such an apalling error.
 
Last edited:
Sir,
I am using a book prescribed for engineering entrance. I feel it may be useful for my GRE Physics exam. Though some of the answers may be wrong, I get so many questions from it. Thank you for your help Sir.
 

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