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The motion of an object is being described by the equation \begin{align*} m\frac{dv(t)}{dt} = mg - \gamma v(t).\end{align*} Determine the solutions of this equation for the paramters: $m=10kg, \gamma = 2kg/s$ and $g= 9.81$, with the following given initial conditions $v(0) = -10,20,30,70$ and $90$ (metes per second).

How should I do that with Maple? I tried this:

Dvgl:=diff(10*v(t),t)=10*9.81-2*v(t);

bvw:=v(0)=-10,20,30,70,90;

dsolve({Dvgl,bvw},v(t));

But then I just get an error: "Found the following equations not depending on the unknowns of the inputsystem: {20,30,70,90}.

Everything works fine with one initial condition, but how can I make it work for several?

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1 Answer 1

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Replace the definition of bvw by

bvw := -10, 20, 30, 70, 90

and then use:

seq(dsolve({Dvgl, v(0) = bvw[k]}, v(t)), k = 1 .. 4)
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  • $\begingroup$ I did what you said, and now it says: Error: found the following equations not depending on the unknowns of the system {-10}. Somehow the first initial condition gets ignored? $\endgroup$
    – Kamil
    Jan 11, 2015 at 12:08
  • $\begingroup$ @Kamil I have no idea why it would say that. For the record, I ran this in Maple version 18. I copied the definition of Dvgl from your post, and the statements in my answer were copied from my Maple session. All this copying using copy/paste, no retyping … I think it's most likely that you made a copying mistake somewhere. $\endgroup$ Jan 11, 2015 at 12:26

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