Physics degrees of freedom problem

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Homework Help Overview

The discussion revolves around a problem involving an ideal diatomic gas undergoing a process with varying pressure and temperature. The participants are examining the implications of degrees of freedom on thermodynamic properties and the relationships between pressure, volume, and temperature during this process.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants are exploring the relationship between degrees of freedom and heat capacity, questioning how to calculate work when neither pressure, volume, nor temperature are constant. There is also a suggestion to graph pressure versus volume to find work, alongside discussions about the implications of a linear pressure versus temperature curve.

Discussion Status

The discussion is active, with participants raising questions about the connections between thermodynamic variables and exploring different approaches to the problem. Some guidance has been offered regarding the relationship between degrees of freedom and heat capacity, but no consensus has been reached yet.

Contextual Notes

Participants are working under the assumption of 5 active degrees of freedom and are navigating the complexities of a non-constant pressure and temperature scenario. There is an acknowledgment of the challenge in determining work and heat in this context.

squib
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A 1.12 mol sample of an ideal diatomic gas at a pressure of 1.00 atm and temperature of 491 K undergoes a process in which its pressure increases linearly with temperature. The final temperature and pressure are 735 K and 1.39 atm. Assume 5 active degrees of freedom.


Neither pressure nor volume nor temp are constant, so I'm confused to how I'm supposed to find work or q.
 
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Have you seen this formula before?

[tex]\Delta Q = \Delta U \pm W[/tex], the [tex]\pm[/tex] is there depending on how you define when is work positive. If I recall correctly [itex]U = \frac {q}{2} n R T[/itex] where [itex]q[/itex] is the numbers of degree of freedom.
 
squib said:
A 1.12 mol sample of an ideal diatomic gas at a pressure of 1.00 atm and temperature of 491 K undergoes a process in which its pressure increases linearly with temperature. The final temperature and pressure are 735 K and 1.39 atm. Assume 5 active degrees of freedom.


Neither pressure nor volume nor temp are constant, so I'm confused to how I'm supposed to find work or q.

A couple of things you need to key on. What is the connection between degrees of freedom and heat capacity? And what can you do with the fact that the P vs T curve is linear?
 
I assume I could graph P vs V and find work, but that seems like more work then should be neccesary. I can find the change in U, or overall energy of the system, the only problem I'm having is with work, which should give me heat since I know U.
 

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