       Re: Projectile motion

• To: mathgroup at smc.vnet.net
• Subject: [mg79892] Re: Projectile motion
• From: ben <benjamin.friedrich at gmail.com>
• Date: Wed, 8 Aug 2007 04:49:31 -0400 (EDT)
• References: <f9912q\$c4n\$1@smc.vnet.net>

```Dear Mike

I haven't worked through your example in detail,
but maybe this snippet of code already gets you going

sol = NDSolve[{x'[t] == 1, x == 0}, x[t], {t, 0, 2},
StoppingTest :> {x[t] > 1}][];
tmax = (x[t] /. sol)[[0, 1, 1, 2]]

Bye
Ben

On 7 Aug., 07:48, Mike <mj... at comcast.net> wrote:
> All:
>
> I'd like to be able to stop the "disk" when it arrives at xmax. Can anyone give me a hint?
>
> Thx,
>
> Mike
>
> Manipulate[
>  Module[{eqns, soln, x, y, t},
>   eqns = {x'[t] == v Cos[Theta], x == 0,
>     y'[t] == -g t + v Sin[Theta], y == 0};
>   soln = Flatten[NDSolve[eqns, {x, y}, {t, 0, p}]];
>   With[{d = x[p] /. soln, h = y[p] /. soln},
>    Graphics[{Blue, Disk[{d, h}, .2]},
>     PlotRange -> {{-.5, 12}, {-.5, 6}}, Frame -> True,
>     PlotLabel ->
>      TableForm[{"Theta =" <>
>         ToString[NumberForm[Theta 180/Pi , {2, 0}]],
>        "vx =" <>
>         ToString[NumberForm[Chop[N[v Cos[Theta]]] , {2, 1}]],
>        "vy =" <>
>         ToString[NumberForm[Chop[N[v Sin[Theta]]] , {2, 1}]],
>        "xmax =" <>
>         ToString[NumberForm[N[(v^2 Sin[2 Theta])/g] , {3, 2}]],
>        "ymax =" <>
>         ToString[
>          NumberForm[N[(v Sin[Theta])^2/(2 g)] , {3, 2}]]}]]]], {{v,
>     5, "Initial Velocity"}, 1,
>   10}, {{g, 9.8, "Gravitational Constant"}, 0,
>   30}, {{Theta, Pi/4 , "Theta"}, 0, Pi/
>   2}, {{p, 0, "Animate"}, 0, 2, ControlType -> Trigger}]

```

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