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Homework Help: Proper Length

  1. Apr 12, 2007 #1
    "proper" Length

    What speed would the spaceship have to travel for its relative length to be half its “proper” length

    Lo = 67m
    L = 33.5


    L = (Lo)(sqr(1-(v^2)/(c^2)))

    Now, I calculate v = sqr((1-(L/Lo)^2)(c^2)) however that gives me an non-real anwer. Clearly my algebra is lacking somewhere.

    Can anyone help me form a proper equation for this?
  2. jcsd
  3. Apr 12, 2007 #2


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    Your algebra looks fine. Your arithmetic seems to be lacking. L/Lo=1/2, 1-(1/2)^2=3/4 etc etc.
  4. Apr 12, 2007 #3
    Ah, yes, I was dividing Lo/L on paper. It is always the simplest things...

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