does anybody besides me find the following wikipedia articles confusing?(adsbygoogle = window.adsbygoogle || []).push({});

http://en.wikipedia.org/wiki/Four-acceleration

a=du/dτ

γ_{u}is the Lorentz factor for the speed (coordinate velocity) u

In an instantaneously co-moving inertial reference frame u = 0, γ_{u}= 1 and dγ_{u}/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

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Wikipedia articles

**Physics Forums | Science Articles, Homework Help, Discussion**