# Homework Help: Solving for Boyle Temperature

1. Oct 1, 2011

### nkk2008

1. The problem statement, all variables and given/known data
So I honestly had to idea where to put this. I know how to solve the problem, but I cannot get Matlab to work. This questions is more of a matlab question. I figured since the underlying problem was physical in nature I would post here, so forgive me if I am wrong.

The problem is attached. I have solved parts 1 and 2. It is part 3 I am having trouble with.

2. Relevant equations

In addition to the one given in the problem,

u(r) = 4e(((r0/r)^12)-((r0/r)^6))

3. The attempt at a solution

I have:
Code (Text):
function problemOne

%declare symbolic Variables
N=6.023e23;
k=1.3806503e-23; %units (m^2)kg/(s^2)K
e=k*213.96; %units of k * 1/K
r0 = 426; %units of pm

syms r T;

%set y to be function inside integral in B
y=exp(((-4*e)*(((r0/r)^12)-((r0/r)^6))/k*T)-1)*(4*pi*(r^2));

%define B in terms of y
B= (-1/2)*N*int(y,r,0,Inf);

%solve for B=0;

solve(B,T)

end

This outputs:

Code (Text):
Warning: Explicit solution could not be found.
> In solve at 81
In problemOne at 21

ans =

[ empty sym ]
I think the problem is in the integral, since

Code (Text):
int(y,r,0,Inf)
yields

Code (Text):
Inf - limit(4*pi*r^3*exp(-1)*exp(4005180207889834777988627621265408/783018253290173*T/r^6)*exp(-23937547659622311621519348000222281120506532855808/783018253290173*T/r^12), r = 0, Right)
What do I do? I thought I had a basic knowledge of Matlab (not an expert by any means), but this is confusing me to no end.

If it is easier to use MathCAD, I do have access to that. I chose not to use it because I have less knowledge of it that I do of Matlab.

Thanks,
Nkk

PS If a mod feels that this would be better suited to another homework section, please move. Again, my apologies of not knowing where to put it.

#### Attached Files:

• ###### Equations of State for Dilute Gases.pdf
File size:
74 KB
Views:
154
Last edited: Oct 2, 2011
2. Oct 2, 2011

3. Oct 2, 2011

### nkk2008

Thanks.

I actually already have a post with this exact problem in the Matlab forums. I realized that that may be the more helpful place to look after I posted this thread.

-Nkk