Molecular interpretation of temperature

  • #1
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:

Answers and Replies

  • #2
125
1
What happens to constants when you need a ratio?
 
  • #3
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
 
  • #4
I like Serena
Homework Helper
6,577
176
Welcome to PF, thattgirljoyy! :smile:

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?
 

Related Threads on Molecular interpretation of temperature

Replies
5
Views
2K
Replies
10
Views
2K
Replies
5
Views
6K
  • Last Post
Replies
4
Views
6K
  • Last Post
Replies
9
Views
3K
  • Last Post
Replies
3
Views
2K
Replies
11
Views
2K
Replies
11
Views
2K
  • Last Post
Replies
13
Views
1K
  • Last Post
Replies
3
Views
7K
Top