Is the Solution Manual's Approach to Internal Energy Calculation Accurate?

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Discussion Overview

The discussion revolves around the accuracy of a solution manual's approach to calculating internal energy, specifically questioning the absence of heat transfer in the solution. Participants explore the implications of this omission and the relationship between work and heat in thermodynamic contexts.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that the solution manual is correct, arguing that the omission of heat transfer is intentional to test understanding.
  • Others express confusion about the reasoning behind the absence of heat transfer, seeking clarification on its relevance to the problem.
  • One participant emphasizes that work is defined as ##P\Delta V## and questions the connection to heat transfer, suggesting that sign errors in equations may have led to misunderstandings.
  • Another participant challenges the notion that work cannot be converted to heat, indicating a need for further discussion on this point.
  • A participant critiques the solution manual for implying that 1 L atm equals 1 J, although they acknowledge that the final answer is correct.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the correctness of the solution manual and the interpretation of work and heat transfer. Multiple competing views remain, with no consensus reached on the implications of the solution manual's approach.

Contextual Notes

Some participants express uncertainty about the definitions and relationships between work and heat, and there are unresolved questions regarding the mathematical steps involved in the calculations.

r12214001
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Homework Statement
My calculation:
|210 X 101.3 – 45| = |-15 X (P)X 101.3 + 45|
Relevant Equations
N/A
Question:
圖片3.png

Solution manual:
圖片2.png

Is the solution manual correct or not? why does not contain heat transfer?
 
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The solution manual is correct. It does not contain heat transfer because it is a trick question. They wanted to test your understanding by providing more information than was necessary to solve the problem. Apparently, you fell for the trick. What puzzles me is how in the world you arrived at your solution.
 
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Chestermiller said:
The solution manual is correct. It does not contain heat transfer because it is a trick question. They wanted to test your understanding by providing more information than was necessary to solve the problem. Apparently, you fell for the trick. What puzzles me is how in the world you arrived at your solution.
why does not contain heat transfer? please educate me.
 
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r12214001 said:
why does not contain heat transfer? please educate me.
Because work is ##P\Delta V##. What has this got to do with the heat transfer?Anyway, if you had gotten the signs correct in your equation, you would have gotten the right answer. What's with those absolute value signs?
 
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Chestermiller said:
Because work is ##P\Delta V##. What has this got to do with the heat transfer?Anyway, if you had gotten the signs correct in your equation, you would have gotten the right answer. What's with those absolute value signs?
TKS for reply
why the energy of work cannot converted to the energy of heat?
 
r12214001 said:
TKS for reply
why the energy of work cannot converted to the energy of heat?
What does TKS mean? Who says work can’t be converted to heat?
 
The solution manual is wrong in implying that 1 L atm = 1 J (although its final answer is correct).
 

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