How to solve 2nd order multiple variable equation with ode45

Hou could i solve this equation using ode45?

[Torsten]

And where is the equation for y_2 ?

[Pedro Martins]

Sorry. Just added it!

[John D'Errico]

Read the help docs for ODE45. In ther, they show how to convert asecond order ODE into a pair of first oder ODEs. So you would have a system of 4 first order ODEs. Its in the help.

Answer 1

[Torsten]

syms t y1(t) y2(t)
syms c2 m1 m2 k1 k2 F
eqn1 = diff(y1,t,2) + c2/m1*(diff(y1,t)-diff(y2,t))+k1/m1*y1+k2/m1*(y1-y2)-F == 0;
eqn2 = diff(y2,t,2) + c2/m2*(diff(y2,t)-diff(y1,t))+k2/m2*(y2-y1) == 0;
sol = dsolve([eqn1 eqn2],'MaxDegree',4)