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!

Homework Help: 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


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    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

    User Avatar

    Staff: Mentor

    Sure. No problem.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted