Molecular interpretation of temperature

Click For Summary

Homework Help Overview

The discussion revolves around the molecular interpretation of temperature, specifically focusing on the relationship between the root mean square (rms) speed of gas molecules and temperature. Participants are exploring how changes in temperature affect molecular speed and examining relevant equations.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants are attempting to relate the rms speed of gas molecules to temperature changes and are questioning how to manipulate equations involving pressure and density. There is a discussion about the implications of constants when dealing with ratios.

Discussion Status

The conversation is ongoing, with participants offering insights and questioning assumptions. Some guidance has been provided regarding the use of formulas to find temperature, but there is no explicit consensus on the interpretations or methods being discussed.

Contextual Notes

Participants are facing challenges due to missing information, such as the specific gas to determine its mass. There is also a mention of conceptual difficulties in proving relationships between rms speed, pressure, and density.

thattgirljoyy
Messages
2
Reaction score
0
i'm trying to do my ap physics summer work, but I've been having a hard time trying to teach this to myself. i do really well in class, but i need a little bit of guidance to help explain how to use the equations the right way.

i'm currently stuck on a question about vrms an it's relation to temp.

Homework Statement


the rms speed of molecules in a gas at 20degrees celsius is to be raised by 1%. To what temperature must it be raised?

Homework Equations


vrms= √3kT/m

The Attempt at a Solution


i don't have any clue where to start if it didn't give me the gas to find it's mass.-i was wondering if i could find someone who could maybe stay in touch for a day or two so i can reach out if i get stuck on anything
 
Last edited:
Physics news on Phys.org
What happens to constants when you need a ratio?
 
okay, the temperature would change by sqrt 2, right ?
essentially about 6 degrees kelvin.

i'm stuck on another problem, it seems to be more conceptual.
it says to prove how
vrms=√P/ρ
P, pressure
ρ, density of the gas

i started with the two equations
P=1/3Nmv^2/V
v^2=3KT/m

i assumed the goal was to get the V from the first equation into the denominator of the second to try to get the density (m/v)
some how all I've gotten to was
P/ρ=[3KT(1/3)N]/m

i'm trying to see if i can get the original 3KT/m to revert back to v^2, but i don't know how to get rid of the (1/3)N/m
 
Welcome to PF, thattgirljoyy! :smile:

thattgirljoyy said:
okay, the temperature would change by sqrt 2, right ?
essentially about 6 degrees kelvin.

It's not too far off 6 degrees... but there is no sqrt 2 involved that I can see... :confused:

Let's put it in formulas:
Before you have some unknown vrms,before at 20 degrees Celsius, or 393 K.
Afterward you have vrms,after=1.01vrms,before at some unknown temperature T.
Substitute and solve for T?
i'm stuck on another problem, it seems to be more conceptual.
it says to prove how
vrms=√P/ρ
P, pressure
ρ, density of the gas

i started with the two equations
P=1/3Nmv^2/V
v^2=3KT/m

i assumed the goal was to get the V from the first equation into the denominator of the second to try to get the density (m/v)
some how all I've gotten to was
P/ρ=[3KT(1/3)N]/m

i'm trying to see if i can get the original 3KT/m to revert back to v^2, but i don't know how to get rid of the (1/3)N/m

Did you consider that m is the mass of one molecule?
What is the mass of all molecules in the volume V?
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 1 ·
Replies
1
Views
5K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
5
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 19 ·
Replies
19
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
3
Views
9K