Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Pendulum Using Lagrange And Hamilton

  1. Oct 9, 2004 #1
    i have been given a problem involving a pendulum, where its support point is accelerating vertically upward. The period of the pendulum is required. Anybody have any idea how to start this one? is it not just 2pi(L/g-a)^1/2?
    Last edited: Oct 9, 2004
  2. jcsd
  3. Oct 9, 2004 #2
    First thing to do is write x, y and x', y' in terms of r and theta (polar coords). Draw a picture to help you visualize, then find the kinetic and potential energies and be sure to take into account the upwards acceleration, so you have both gravity and this upwards accelration acting on the mass. Then find the Lagrangian and/or Hamiltonian and use one of them to find the equations of motion.
  4. Oct 10, 2004 #3
    The period of a pendulum is not [tex] \nu = 2\pi \sqrt{\frac{L}{g}}[/tex] that is only an approximation to the right expression, which we can't solve exactly
    Last edited: Oct 10, 2004
  5. Oct 10, 2004 #4


    User Avatar
    Science Advisor

    skrao -- Ask yourself what the period would be if the upward acceleration was equal to g?

    reilly Atkinson
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?