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2 replies

W
Werner_E25-Diamond I
25-Diamond I
May 11, 2020

Two problems in your MC15 sheet:

1) wrong syntax of Odesolve (you don't have to provide the function name theta in MC15)

2) the expression on the right hand side of your ODE takes non-real values if theta goes above 45 degree
I coped boldly with the last situation by applying the Re() function 😉

 

Now you get a solution, but its constant 45°

 

Werner_E_1-1589211690048.png

 

 

    V
    ValeryOchkov24-Ruby IVAuthor
    24-Ruby IV
    May 11, 2020

    Thanks!

    But why I get a constants, not a function - angle of the pendulum as function of time?

    A
    AlanStevens19-Tanzanite
    19-Tanzanite
    May 11, 2020

    Total energy is constant throughout, so the value under the square root sign of the numerator of the RHS of your ODE is always zero; hence theta goes nowhere (as you can see from Werner's graph)!!

     

    Alan 

    A
    AlanStevens19-Tanzanite
    19-Tanzanite
    May 11, 2020

    If you wish to get the equations of motion from conservation of energy Val, you need to do the following:

     

    g0.jpg

    Alan

     

      V
      ValeryOchkov24-Ruby IVAuthor
      24-Ruby IV
      May 11, 2020

      Thanks Alan!

      I see my bug!

      See please Problem 3 in the Manuscript!

       

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