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Mass in SR

  1. Aug 18, 2009 #1
    is the mass invariant in special relativity or what ?
    i'm so confused , is the mass of a body change with the change of the body's speed ?
  2. jcsd
  3. Aug 18, 2009 #2


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    Two different conventions are being used. The one favored by most people today is this one:

    Mass is invariant. It's denoted by [itex]m[/itex]. The quantity


    is called "energy". If we have to use a name for the quantity


    we call it "relativistic mass", but we prefer not to use it at all.

    The other convention is to use the notation [itex]m_0[/itex] and the term "rest mass" for what I would call "mass", and the notation [itex]m[/itex] for what I would call "relativistic mass". This convention makes "mass" a function of speed:

  4. Aug 18, 2009 #3


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    Please read an entry in our FAQ in the General Physics forum.

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