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Stuck on special relativity

  1. Oct 30, 2009 #1
    1. The problem statement, all variables and given/known data

    An unstable high-energy particle is created in the laboratory, and it moves at a speed of 0.978c. Relative to a stationary reference frame fixed to the laboratory, the particle travels a distance of 1.38x10-3 m before disintegrating.

    (a) What is the proper distance traveled?
    (b) What is the distance measured by a hypothetical person traveling with the particle?
    (c) What is the proper lifetime?
    (d) What is the dilated lifetime?

    2. Relevant equations



    3. The attempt at a solution

    Stuck on part A:
    L= 1.38x10-3m

    (gamma)=1/sqrt(1-(v/c)2)= 1/sqrt(1-(.978)2)= 4.79

    L0=L x (gamma)= (1.38x10-3m)(4.79)= .00662m

    Did something wrong and cannot figure it out. Please help!
  2. jcsd
  3. Oct 30, 2009 #2

    Doc Al

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    Staff: Mentor

    According to the particle frame, is the distance traveled shorter or longer than seen in the lab frame?
  4. Oct 30, 2009 #3
    Distance should be greater for L0 because (gamma) is going to always be greater than 1. Right? It should be shorter in the lab frame compared to particle frame.
    Last edited: Oct 30, 2009
  5. Oct 30, 2009 #4

    Doc Al

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    Staff: Mentor

    Realize that the distance is measured at rest in the lab frame, so I suppose that's the distance they want as the "proper distance". From the view of the particle frame, that distance is moving. What happens to moving lengths? (That's really part b, not part a. Oops!)
  6. Oct 30, 2009 #5
    Lengths contract when moving. so the particle should be the shorter distance. So part a is the given part of the question. Ok parts a and b make
    Last edited: Oct 30, 2009
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