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From: lindley@ut-ngp.UUCP (John L. Templer)
Newsgroups: net.math
Subject: Re: Solution to a weighty problem?
Message-ID: <1271@ut-ngp.UUCP>
Date: Sat, 2-Feb-85 20:42:05 EST
Article-I.D.: ut-ngp.1271
Posted: Sat Feb  2 20:42:05 1985
Date-Received: Fri, 8-Feb-85 00:24:07 EST
References: <423@decwrl.UUCP>
Organization: U.Texas Physics Department; Austin, Texas
Lines: 34

> Does anyone know the solution y=f(t) for the following differential equation?
> 
> 		 2 ,,            ,
> 		t y  (t)=K      y (0)=K1,  y(0)=K2
>                                    ,,                                ,
> where K, K1 and K2 are constants, y   is the second derivitive, and y is the
> first derivitive and t is the independant variable?  This is an equation of
> the motion of an object under the influence of gravity as a function of time.
> 
> Mike Moroney
> ..!decvax!decwrl!rhea!jon!moroney

Isn't this an example of a variables-seperable equation?  I.e., the solution
looks something like this:

	 2   -2    2
	d t*t = K*d y

Bit hard to write that on an ascii screen.  Oh well, what it says is:

"The second differential of t divided by t squared equals K time the
second differential of y."

Now just integrate twice and plug in the initial conditions.
Or have I missed something?

-- 

                                           John L. Templer
                                     University of Texas at Austin

    {allegra,gatech,seismo!ut-sally,vortex}!ut-ngp!lindley

                 "and they called it, yuppy love."