Double Pendulum Verification Please

[icecube87]

Homework Statement

I have to get the equations of motion for the double pendulum and then represent it in State Space form.

Homework Equations

Now as you can see in the check.jpg attachment, i assumed earlier that both pendulum rods have the same length and both pendulums have the same mass. Therefore I effectivelly got rid of the mass (1,2) variables from the whole expression for both w1 and w2. I have a feeling though that this might be wrong as it should not be possible to calculate both w1dot and w2dot without mass (even if they are the same). (logically speaking now)

Can someone tell me if I'm doing the right thing? If not, i would be really grateful if you could tell me what's wrong. Thanks

 

[BigJDubs]

!The Attempt at a SolutionYes, it is correct to assume that both pendulums have the same mass and length. This simplifies the equations of motion for the double pendulum since you can use the same mass and length in each equation. This means that you will not need to include the mass variables in the equations for w1dot and w2dot.