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Translating and rotating rod

  1. Sep 7, 2008 #1
    if a rod is moving close to the speed of light in its linear velocity and rotating at some angular velocity will the rod's length and width change as it rotates making it look all funky or will it do something else because it can't be treated as a rigid body? If it does do what i mentioned above then its angular momentum is changing and that means there is torque.
  2. jcsd
  3. Sep 7, 2008 #2


    User Avatar
    Science Advisor

    Because its endpoints cannot move faster than the speed of light, relative to some external observer (You say it is "moving close to the speed of light". You mean, of course, relative to this observer.) it will appear to bend. As has been said here many times, there is no such thing as a "rigid body" in relativity.
  4. Sep 7, 2008 #3


    Staff: Mentor

    Depends, do you call http://commons.wikimedia.org/wiki/Image:Relativistic_Rolling_Wheel.png" [Broken]"funky"?

    PS I cannot vouch for the accuracy of these pictures, it is a wikipedia link after all, but they seem about right.
    Last edited by a moderator: May 3, 2017
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