Finding the constants of an ODE

Forum|Forum|9 years ago
August 24, 2016
16 replies
3783 views

Hello everyone,

I have the differential equation m∙x ̈+C∙x ̇+k∙x=0 and i know only the mass, do you know if there is a way to find the coefficients C and K? do you think this can be solved with odesolve if i declare some initial conditions?

Calculus_Derivatives

S

StuartBruff

23-Emerald V

Iulia Savu wrote:

Hello everyone,

I have the differential equation m∙x ̈+C∙x ̇+k∙x=0 and i know only the mass, do you know if there is a way to find the coefficients C and K? do you think this can be solved with odesolve if i declare some initial conditions?

I'd be interested to see any answers to this showing how, but I don't think you can. AFAICT, if you know the mass and initial values (eg, position, speed), then you will still need to know what C and k are to know how the system will evolve. For example, if I attach a weight to the bottom of a (massless) spring, and pull it down, then I won't know how quickly the spring will pull it back up unless I know how strong the spring is. You may have a chance if you know the final values as well, though.

Stuart

24-Ruby IV

23-Emerald V

So how do I find C and k, given m, x(0) and x'(0), Valery?

Stuart

V

ValeryOchkov

24-Ruby IV

Two equs with two unknowns

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-MFra-

21-Topaz II

Knowing the general integral of the differential equation and some initial conditions, it is possible to determine the coefficients P and Q , in your case, C and k.

I

isavu

Author

1-Visitor

So i need to use the case of real roots, because i need real values that are going to be used later as parameters, and i don't understand how am i going to extract the values of c1 and c2 . Do i use the initial conditions? Because i don't think that's going to work...