- #1

- 39

- 0

## Homework Statement

m = 1 kg, l = 1 m, theta 1 and 2 are small

I want to work out the natural frequencies (2) of this 2 DOF system through taking torques about the fixed point on the ceiling. I've done it using numerous fixed points and just cannot get the right answer.[/B]

## Homework Equations

sum of torques = I . alpha

## The Attempt at a Solution

Taking that cos theta = 1 and sin theta or tan theta = theta and acw moments are pos,

I get that for the lowest mass:

-mg (theta 2 + theta 1) + T2(theta1 + theta 2) - 2T2theta2 = 4alpha

for highest mass: -mgtheta1 - T2theta1 + theta2T2 = alpha.

Does anyone else get this? I want to solve it via torques and not any other method. NB: T2 = tension in lowest massless string.[/B]