Adiabatic Expansion of a Gas: Final Pressure-Volume Product Calculation

AI Thread Summary
The discussion focuses on calculating the final pressure-volume product for a diatomic gas undergoing adiabatic expansion. The initial conditions include a pressure of 365 Pa and a volume of 70 m³, with the gas doing 101 J of work. The user correctly identifies the degrees of freedom as 3, leading to a value of ϒ=1.4 for diatomic gases. Despite applying the adiabatic work equation, the user is uncertain about their calculations, questioning whether they are approaching the problem correctly or if the answer might be incorrect. The thread highlights the importance of understanding degrees of freedom in gas behavior during adiabatic processes.
vetgirl1990
Messages
85
Reaction score
3

Homework Statement


A gas consisting of diatomic molecules that can rotate but not oscillate at a given range of temperatures expands adiabatically from pressure of 365Pa and volume of 70m3, doing 101J of work, while expanding to a final volume. What is its final PV (pressure volume) product?

Homework Equations


For an adiabatic expansion:
W = (1/ϒ-1)(pfvf - pivi)

The Attempt at a Solution


i) Degrees of freedom: 3
Therefore, ϒ=1.4

ii) Plug and chug of the equation above.
W = (1/ϒ-1)(pfvf - pivi)
101 = (1/1.4-1)(pfvf - 365*70)
101 = 2.5pfvf - 63875
pfvf = 25590 Pa / m3

I'm fairly certain I found the degrees of freedom correctly, and the latter part of my calculations is pretty straightforward... Still getting the wrong answer, however. Chance that the answer is wrong? Or am I approaching the problem incorrectly?
 
Physics news on Phys.org
Isn't it 3 degrees of freedom for a monatomic gas?
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Trying to understand the logic behind adding vectors with an angle between them'
My initial calculation was to subtract V1 from V2 to show that from the perspective of the second aircraft the first one is -300km/h. So i checked with ChatGPT and it said I cant just subtract them because I have an angle between them. So I dont understand the reasoning of it. Like why should a velocity be dependent on an angle? I was thinking about how it would look like if the planes where parallel to each other, and then how it look like if one is turning away and I dont see it. Since...
Back
Top