[Date Index]
[Thread Index]
[Author Index]
Re: newbie here,, need help with parametrics
*To*: mathgroup at smc.vnet.net
*Subject*: [mg96503] Re: newbie here,, need help with parametrics
*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
*Date*: Sun, 15 Feb 2009 03:19:34 -0500 (EST)
*Organization*: The Open University, Milton Keynes, UK
*References*: <gn5u3e$gko$1@smc.vnet.net>
In article <gn5u3e$gko$1 at smc.vnet.net>, "R.J." <nemocamaro at epix.net>
wrote:
> I am using Mathematica and i'd rather be using derive,,,,, but anyways,,
> heres the problem i have to do, a baseball is thrown from the stands 32 feet
> from the ground at an angle of 30 degrees above the horizontal, initial
> velocity is 32 feet per second.
>
> what i want to do is find how to plot this in mathematica,, the graph i keep
> getting says it hits the ground after .8 seconds, and i know thats not
> right,,, here is the formula i am using
>
> r = (x + v Cos a) t) i + (y + (v Sin a) t - 1/2 gt^2) j
>
> where x is the initial x position and y is the initial height, v is the
> initial velocity a is the angle (30*) t is time and g is the gravitational
> constant..
>
> i'm stuck,,, any help?
Note that you should have posted the actual code you used, so it would
have been possible to give you precise recommendations on what you did.
Anyway, assuming I have correctly interpreted your requirements and
notation (as well as correctly filled in the missing information), the
following expressions produce two plots that suggest that the ball hits
the ground for 4 < t < 5 seconds. Now, why not using Solve[] to get the
precise value?
x[t_] = (x + v*Cos [a])* t;
y[t_] = (y + (v*Sin[a])*t - 1/2 *g*t^2);
ParametricPlot[{x[t], y[t]} /. {x -> 0, y -> 30, v -> 32, a -> Pi/6,
g -> 9.81}, {t, 0, 4}]
ParametricPlot[{x[t], y[t]} /. {x -> 0, y -> 30, v -> 32, a -> Pi/6,
g -> 9.81}, {t, 0, 5}]
Regards,
--Jean-Marc
Prev by Date:
**Re: Re: New free introductory book on Mathematica**
Next by Date:
**Re: Functions inside modules with external definitions**
Previous by thread:
**Re: newbie here,, need help with parametrics**
Next by thread:
**Re: newbie here,, need help with parametrics**
| |