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!

Epicyclic motion and precession

  1. Apr 6, 2014 #1
    Imagine I am standing but not moving forward/backward, but I am rotating my body about my own axis. Now imagine if I moved in a circular path as I was spinning on my own axis. Is this considered to be precessing (assuming the axis of rotations are always in the z direction)?

    My friend says it is, but I disagree. Wouldn't I always have the same angular momentum? And torque induced precession requires a change in L? Now I know there is a torque-free precession, but I didn't quite understand it. Can someone clear this up?
  2. jcsd
  3. Apr 7, 2014 #2


    User Avatar
    Science Advisor
    Gold Member

    See http://en.wikipedia.org/wiki/Precession

    If you are standing straight there is no axial precession; precession induces a wobble in the axis of a gyroscope.

    So your friend is wrong - unless he means something else by the term precession.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook