00:01
This is problem 10, chapter 15.
00:03
And so our ideal gas equation is pv equals nrt, as you know.
00:09
And then the expression for eternal energy of an ideal gas is written as u equals d over 2 and kt, where n is equal to n and a, and that is avagadro's number, or n .a is abagadro's number, and then k is the boltzman's constant.
00:30
Where k equals r over n a and t is the temperature and so now using this equation here we can go ahead and substitute some of these values to get it in a form that is actually usable so u is going to be equal to d over two and then we'll go ahead and substitute our values so n equals n times n times r over n .a.
00:54
And these will cancel times t.
00:58
And so then our u is going to be equal to d over 2 and rt.
01:05
And our d is our degrees of freedom.
01:08
And so now we can go ahead and understand that air is mostly comprised of nitrogen, which is a diatomic gas.
01:16
So consider the air and the tire to be diatomic.
01:20
And the degrees of freedom for a diatomic gas is five.
01:25
So we need to substitute five in for d in our equation.
01:28
So u is going to be equal to 5 over 2 times nrt.
01:35
And so now we can go ahead and substitute our pv for nrt...