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Re: Help with solving ODE

• To: mathgroup at smc.vnet.net
• Subject: [mg81793] Re: Help with solving ODE
• From: "Kevin J. McCann" <kjm at KevinMcCann.com>
• Date: Wed, 3 Oct 2007 06:13:03 -0400 (EDT)
• References: <fdvdq7$sul$1@smc.vnet.net>

First, you should learn to use Mathematica. This one is pretty basic.

Try

DSolve[y''[t]+b y'[t]==c,y[t],t]


Pioneer1 wrote:
> Hi,
> 
> Can anyone help solve this linearized differential equation:
> 
> Iy'' + ky' = 2GMmd/a^2
> 
> Primes are time derivates of y (=theta=excursion angle). Is it
> possible to solve this for the initial conditions y(0)=0 and y'(0)=0?
> 
> I got the solution at sci.math for the non-linear version and I want
> to compare the two. Here's the link to sci.math thread:
> 
> http://groups.google.com/group/sci.math/browse_thread/thread/a6ee2f782df09625/53cf5573d354a3ab#53cf5573d354a3ab
> 
> Further information is also available at sci.physics.research
> 
> http://groups.google.com/group/sci.physics.research/browse_thread/thread/d391940cc173f9dc/eed90e6c3fee0edc#eed90e6c3fee0edc
> 
> Parameters are:
> 
> 
>>y = theta = excursion angle in radians
>>A = I = moment of inertia = 13,138,117.34 g cm^2
>>B = R = damping = for now I assume this to be zero
>>C = k = torsion constant  = 724.68 g cm^2 sec^-2
>>d = moment arm = 93.09 cm
>>D = 2GMmd = 2 * 6.67*10^-8 * 158100 * 729.8 * 93.09 = 1432.82
>>a = distance between weights = 22.10 cm
> 
> 
> I would truly appreciate help with this. Thanks
> 
>