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From: Harold A. Climer on 4 Sep 2008 11:46
On Thu, 04 Sep 2008 03:52:48 -0500, "John H Meyers"
<jhmeyers(a)nomail.invalid> wrote:

>Erratum:
>
>> If you did not specifically solve for one chosen variable at a time,
>> but let R.S. [ALL] give the MES liberty to "walk whichever way it wants..."
>
>L.S. [ALL] is "solve all"; R.S. [ALL] is "Progress catalog" (post-mortem).
>
>Maybe "Errata" applies, but as being awake right now is a bigger error,
>I'll correct that one next :)
>
>G'night!
>
>.

I finally figured out how to get the calculator to come up with the
correct results.

You have to solve the equation 1/2gt^2 -Voyt-Y =0 using the poly
solver for t.
If you plug in the positive root for the time t into the M.E. solver
in the Equation Library as well as the other variables mentioned in
the previous posts it comes out correctly. It seems you have to force
the calculator to use the positive root.
Harold A. Climer
Dept Of Physics Geology & Astronomy
U.T. Chattanooga
Room 406A Engineering,Math & Computer Sicence Building
615 McCallie Ave.
Chattanooga TN 37403
Harold-Climer(a)utc.edu
From: John H Meyers on 4 Sep 2008 13:19
On Thu, 04 Sep 2008 10:46:24 -0500, Harold A. Climer wrote:

[re "Projectile Motion" in calculator Equation Library]

> It seems you have to force the calculator to use the positive root.

It depends on the equation(s), initial conditions (even solver state,
which governs which equation and variable may next be used by MES),
and value(s) left over from previous solutions.

Even the "single equation" numeric solver (30 MENU)
always starts from whatever "guess" (or list of one, two or three guesses)
is currently stored in the currently changing variable, or { 0. 1. }
if that variable is not yet created or if its current numeric value is zero
(this actually pre-biases many initial solutions in the "positive" direction).

So if you store a larger positive guess and then solve,
you are more likely to get the positive answer,
even though both answers are probably meaningful
for this problem -- that is to say, since
"what goes up comes down," the general question
"when does a projectile on this trajectory have altitude Y"
pretty much generally has TWO correct answers all the time,
regardless of your being more interested in one than the other.

It is possible to "bias" personal equations to discourage "root hunting"
in regions not of interest, but the equations already hard-coded
into the Equation Library are pure and "politically/physically correct,"
automatically having "no boundaries or prejudices"
to prevent looking back in time to that part of the true trajectory
that could have existed before your release of the projectile
(if fired from another point, even earlier, for example),
just as all equations of "Classical Physics"
know no distinction between past and future,
permitting the universe to "evolve" in either direction,
thus long confounding searchers looking for the elusive reason
for an "arrow of time" that somehow resists our "growing younger,"
or even makes a dropped and shattered flower pot
somehow unlikely to be "thrown back together again,"
or a fired bullet to return to the barrel of the gun
and not have killed anyone.

http://en.wikipedia.org/wiki/Arrow_of_time
http://en.wikipedia.org/wiki/Entropy_(arrow_of_time)
http://physicsworld.com/cws/article/print/1327 [Particle Physics 1998]
http://www.amazon.com/Arrow-Time-Roger-Highfield/dp/0449907236 [1992]
http://cosmicvariance.com/2008/05/21/the-arrow-of-time-in-scientific-american/

[r->] [OFF]
From: cesarv on 4 Sep 2008 13:48
On Sep 3, 6:32 pm, Harold A. Climer <Harold-Cli...(a)utc.edu> wrote:
> I  use the Equation Library to check  the projectile  motion results
> of the students.
> Lately however I have been getting some strange results. I have been
> plugging the values for Xo,Yo,Yfinal, theta, and the value of Vo.
> When I solve for t, etc I keep getting negative values for t, which is
> impossible.
> Is there a flag that I have forgotten about that I need to set to get
> the positive value for the time?
> Could other variables be confusing the solver? HELP!!!
> This has happened with both my GX and my HP50G

You can use the comand MSOLVER2 of the library 1210: Comandos V1.02 at
the end of this page.

http://cesarv.wetpaint.com/page/L1210+COMANDOS.

You can give aproximations to the unknows variables.
You can see which variables are knows or unknows in one screen.
You can see help and the equations in the same screen.
The number of variables you can use is between 2 and 63.

_________________________________________________
César Vásquez Alvarado
Lima Perú
http://cesarv.wetpaint.com/
From: Veli-Pekka Nousiainen on 4 Sep 2008 16:12
Hola!
Is it possible to have this library and instructions
totally in English, please?!
Hermanos-Petros
==============================================
You can use the comand MSOLVER2 of the library 1210: Comandos V1.02 at
the end of this page.

http://cesarv.wetpaint.com/page/L1210+COMANDOS.

You can give aproximations to the unknows variables.
You can see which variables are knows or unknows in one screen.
You can see help and the equations in the same screen.
The number of variables you can use is between 2 and 63.

_________________________________________________
C�sar V�squez Alvarado
Lima Per�
http://cesarv.wetpaint.com/


From: cesarv on 5 Sep 2008 17:05
On 4 sep, 15:12, "Veli-Pekka Nousiainen"
<velipekka.nousiai...(a)saunalahti.fi> wrote:
> Hola!
> Is it possible to have this library and instructions
> totally in English, please?!
> Hermanos-Petros

Yes, it's posible.
You must have patience.
Don't send me virusses, please.
The version 1.03 of the library in:
http://cesarv.wetpaint.com/page/L1210+COMANDOS
Now, also in your language.
_________________________________________________
César Vásquez Alvarado
Lima Perú
http://cesarv.wetpaint.com/
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