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: 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


    User Avatar
    Science Advisor
    Homework Helper

    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...

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook