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Homework Help: Work and special relativity

  1. Feb 25, 2005 #1
    ok i have a question from mastering physics i thought i was doing it right but it gives me an incorrect answer.

    How much work must be done on a particle with a mass of m to accelerate it from rest to a speed of v_1? (Express the answer in terms of mc^2.)

    I figured that this would just be the kenetic energy which is givin by

    K= mc^2/(sqrt(1-(v/c)^2) - mc^2

    so i factored out an mc^2 and was left with

    work= (1/sqrt(1-(v/c)^2) -1)*mc^2

    but mastering physics says that the answer does not depend on c.
    i dont see how this is possible

    thanks for the help
  2. jcsd
  3. Feb 25, 2005 #2
    Express the answer in terms of mc^2. the answer is [tex] \gamma -1 [/tex]
  4. Feb 25, 2005 #3
    yes, that is my problem, the definition of gamma is 1/(sqrt(1-9V/c)^c)
    so gamma itself contains a c and i dont think mastering physics will except the variable expression gamma as part of the answer because it is no where to be found in the problem.
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