       Re: Projectile motion

• To: mathgroup at smc.vnet.net
• Subject: [mg79882] Re: Projectile motion
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Wed, 8 Aug 2007 04:44:18 -0400 (EDT)
• Organization: Uni Leipzig
• References: <f9912q\$c4n\$1@smc.vnet.net>

```Hi,

a) it is not wise to solve the ode every time even when the
analytical solution can be found and the time where the ball
hit the ground is known to be
2 v Sin[Theta]/g
b)

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, 2 v Sin[Theta]/g}]];
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[(v2 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 v Sin[Theta]/g, ControlType -> Trigger}]

will do that.

Regards
Jens

Mike 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}]
>

```

• Prev by Date: Re: Beta function, Integral
• Next by Date: Can model parameters be global?
• Previous by thread: Re: Projectile motion
• Next by thread: Re: Projectile motion