1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Lagrange equations:

  1. Oct 28, 2012 #1
    Consider a rectilinear rod (A-B) with negligible mass that is attached, without friction, to a vertical OZ axis. The rod rotates about that axis with a constant angular velocity ω and it maintains a angle α with OZ.

    A particle of mass m moves about the rod and it is attracted by the gravity.

    a) Indicate, and justify the degrees of freedom of the material point.

    To write the degrees of freedom i have to know the equations of x, y and z.

    My problem is the z component equation.

    For x and y we have the following equation:
    x^2+y^2 = r^2

    r is the radius (A-B)

    Now i need the equation for z..

    any types?
    Last edited: Oct 28, 2012
  2. jcsd
  3. Oct 30, 2012 #2


    User Avatar
    Homework Helper
    Gold Member
    2017 Award

    If I'm understanding the setup, wouldn't r and z make up two legs of a right triangle with ##\alpha## as an angle in the triangle? So, z can be expressed in terms of r and ##\alpha##.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook