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Help with solving ODE

• To: mathgroup at smc.vnet.net
• Subject: [mg81772] Help with solving ODE
• From: Pioneer1 <1pioneer1 at gmail.com>
• Date: Wed, 3 Oct 2007 02:31:57 -0400 (EDT)

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

• Follow-Ups:
  • Re: Help with solving ODE
    • From: Murray Eisenberg <murray@math.umass.edu>