Stony Brook University   MAT 303: Calculus IV
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Here are several applets demonstrating concepts discussed in MAT 303 (will open in new windows):
  • Mechanical Vibrations:
    Free damped vibrations
    This is the graph of the solution of the equation x''+bx'+kx=0. You may vary parameters b and k and the initial values x(0) and x'(0) (just click on the b or k slides in the lower left corner or the x(0)-x'(0) plane above them to change the values). Clicking on the Roots button will show the roots of the corresponding characteristic equation.
    Non-free damped vibrations
    This is the graph of the solution of the equation x''+bx'+kx=cos(ωt). Here you may also change the values of b, k, x(0) and x'(0) as well as the external frequency ω. The blue graph on the right corresponds to the solution of the associated homogeneous equation, xc, the green graph to the particular solution xp. The yellow graph is the solution x=xc+xp.
  • Systems of equations:
    Phase Portraits
    To work with this applet, turn off the "Companion Matrix" feature (click on the blue square to the left of the words "Companion Matrix").
    In the lower right corner, you have the slides for parameters a,b,c,d. Above is the phase portrait for the system
        x'=ax+by
        y'=cx+dy
    Changing values of these parameters changes the phase portrait.
All applets are courtesy of the d'Arbeloff Interactive Math Project at MIT.