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Modeling Gravity with Matlab

  1. Sep 1, 2006 #1
    I am trying to model gravity with vector field lines in Matlab. I can kinda do it with a 2D plot, but I cant quite grasp the "scale" field in the quiver function. I then tried to model in 3D vectors and I just made a mess w/ that. Below is my simple 3D and 2D code.

    Help w/ this code or if you know a better way to do this would be nice!

    non working 3D plot
    [X Y Z] = meshgrid(-3:.1:3);
    r = sqrt(X.^2 + Y.^2 + Z.^2);
    ag = 1./r.^2;
    [ax ay az] = gradient(ag);
    quiver3(X, Y, Z, ax, ay, az)

    Poor 2D plot
    M = 1; %Mass of Earth in kg
    G = 1; %Gravitational Constant
    R = 1; %Radius of Earth in m
    [x y] = meshgrid(-3:.75:3);
    r = sqrt(x.^2 + y.^2);
    ag = G*M./r.^2;
    [ax ay] = gradient(ag);
    contour(x,y,r,[R R])
    colormap cool
    hold on
    scale = 0;
    quiver(x,y,ax,ay,scale)
    hold off
     
    Last edited: Sep 1, 2006
  2. jcsd
  3. Sep 1, 2006 #2

    Integral

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    Gold Member

    Prehaps you could post an image file of some sort. I cannot open your .m file and will not aprove it without doing so.
     
  4. Sep 1, 2006 #3
    is this better?
     
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