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A Falling Rod's Intersection Moving Faster Than Light?

  1. Mar 7, 2013 #1
    1. The problem statement, all variables and given/known data
    There is a rod falling at a speed v that makes an angle θ with the x-axis as it falls. Is it possible for the intersection point to move faster than light as it falls.


    2. Relevant equations



    3. The attempt at a solution

    I have done the geometrical calculations and I think yes, it does (which is fine because it's not a particle moving faster than light, only an image) but I am not sure if I am right.

    Since it's moving downwards only, the only compression would be vertical and not horizontal so the speed would not decrease. Can anyone tell me if I am correct or not?
     
  2. jcsd
  3. Mar 7, 2013 #2

    haruspex

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    I assume the rod is not rotating.
    I don't think it even needs to be falling at relativistic speeds, it just needs a very shallow angle. But I'm no expert on relativity, so I may be missing some subtlety.
     
  4. Mar 7, 2013 #3

    Doc Al

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    Sure. No problem.
     
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