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Homework Help: Relativity problem involving a muon

  1. Oct 15, 2014 #1
    1. The problem statement, all variables and given/known data
    A muon is a subatomic particle with an average lifetime of 2.2 microseconds when stationary. In a burst of cosmic rays in the upper atmosphere, muons are observed to have a lifetime of 16 microseconds. What speed are they travelling at to achieve this?

    2. Relevant equations
    Time Dilation, Length Dilation, Mass Dilation, along with a few astrophysics formulas

    3. The attempt at a solution
    So I'm thinking this is relativity.
    I used the time dilation formula:

    and worked out the velocity to be 2.972 x 108 m/s

    My maths is fine (it doesn't need checking but check it if you want to). What I really need to know is if this is the correct process?
  2. jcsd
  3. Oct 16, 2014 #2


    User Avatar

    Staff: Mentor

    Yes, that's the right formula to be using.
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