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Wikipedia articles

  1. Sep 25, 2008 #1
    does anybody besides me find the following wikipedia articles confusing?

    http://en.wikipedia.org/wiki/Four-acceleration
    a=du/dτ
    γu is the Lorentz factor for the speed (coordinate velocity) u
    In an instantaneously co-moving inertial reference frame u = 0, γu = 1 and dγu/dτ = 0, i.e. in such a reference frame
    A =(0,a)
    Therefore, the four-acceleration is equal to the proper acceleration that a moving particle "feels" moving along a world line.

    should read:
    Therefore, the four-acceleration within that co-moving inertial reference frame is equal to the proper acceleration that a moving particle "feels" moving along a world line.


    http://en.wikipedia.org/wiki/Proper_acceleration
    The proper acceleration 3-vector, combined with a null time-component, yields the object's four-acceleration. (this is just plain wrong)

    even though below that:
    http://en.wikipedia.org/wiki/Proper_acceleration#Viewed_from_a_flat_spacetime_slice
    it correctly states:
    proper acceleration α and coordinate acceleration a are related[6] through the Lorentz factor γ by α=a*γ^3
    Hence the change in proper-velocity w=dx/dτ is the integral of proper acceleration over map-time t (coordinate time)
    and gives these formulas:
    http://upload.wikimedia.org/math/f/3/f/f3fd7fcce9b254111e10ca5bae382511.png

    you can check that the derivative of proper velocity with respect to coordinate time is a*gamma^3 by entering v[t]/sqrt[1-((v[t])^2)] into this http://calc101.com/webMathematica/derivatives.jsp#topdoit
     
    Last edited: Sep 25, 2008
  2. jcsd
  3. Sep 25, 2008 #2
  4. Sep 25, 2008 #3
    I have edited the 2 wikipedia articles in question. I would very much appreciate it if someone would double check my work.
     
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