1. Not finding help here? Sign up for a free 30min 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!

Special relativity - observing spinning objects

  1. Oct 2, 2007 #1

    Mentz114

    User Avatar
    Gold Member

    I did a thought experiment - suppose we have a simple clock comprising a disc rotating with constant angular velocity. We can read off time inervals by counting the revs.

    Another observer, passing at constant velocity will see the disc rotating at a slower rate, since moving clocks run slower.

    Does this mean that all spinning objects appear to be spinning slower from another frame ?

    In other words, does angular velocity transform like time in SR ?
     
    Last edited: Oct 2, 2007
  2. jcsd
  3. Oct 2, 2007 #2
    Yes, I think your observation is correct.

    Eugene.
     
  4. Oct 2, 2007 #3

    Mentz114

    User Avatar
    Gold Member

    Hi Eugene,
    yes, it seems inevitable. It is a bit puzzling because angular velocity has dimension of reciprocal time.

    I wonder if angular momentum transforms the same ?

    M
     
    Last edited: Oct 3, 2007
  5. Oct 2, 2007 #4
    To be more precise, I think that the rotation period of a moving object should increase by the factor [itex] \gamma = (1-v^2/c^2)^{-1/2}[/itex]. Then the rotation speed of such an object should go down, i.e., the factor is [itex] \gamma^{-1} [/itex].

    Eugene.
     
  6. Oct 3, 2007 #5

    Mentz114

    User Avatar
    Gold Member

    Agreed. Nothing to it. It's only a kinematic effect in any case. Thanks for the input.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Special relativity - observing spinning objects
  1. Special relativity (Replies: 3)

  2. Special relativity (Replies: 1)

Loading...