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Homework Help: Solving for Boyle Temperature

  1. Oct 1, 2011 #1
    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:

    Last edited: Oct 2, 2011
  2. jcsd
  3. Oct 2, 2011 #2
  4. Oct 2, 2011 #3
    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
     
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