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Homework Help: Lagrange: block pendulum

  1. Jun 14, 2015 #1

    I'd like to ask for help with one problem :) thank you in advance.

    1. Write the equations for kinetic and potential energy for the pendulum with rectangular prism of size a*b*c (width, length, depth). With the Lagrange's equation get the equation of motion. The block is homogeneous with mass m. We also have a torsion spring with coefficient k. J is a moment of inertia. Angle is q (or phi if you prefer).

    So it is a theoretical task. The bold characters are supposed to be known as seen on the sketch.


    2. Am I right with this?

    Wp (potencial energy) = m * g * b/2 * (cos(q) - 1)

    Wk (kinetic energy) = 1/2 * J * ω^2

    ω = dot(q)

    J = 1/12 * m * (a^2 + b^2) + m * (b/2)^2

    Where do I include the spring?
  2. jcsd
  3. Jun 19, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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