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Homework Help: Muon Half Life

  1. Feb 24, 2010 #1
    Hi All,

    I'm trying to do a Relativity problem and I'm having trouble.

    There is a detector on a balloon at 2000 meters above the earth that in one hour has detected 650 muons that normally have a half life of 1.5 microseconds. They are traveling at .99c towards the earth. How many are detected at the earth in one hour.

    Now due to time dilation, I get 10.633 microseconds for the half life relative to ground observers. That seems pretty reasonable.

    Now I figure that all I need to know is how long it takes for them to travel 2000 meters and that seems to be a classical calculation. Time =2000 meters/.99c but my answer is way off.

    Am I approaching this correctly? I am wondering about calculating the time it takes the muons to reach the ground in a classical manner?

    The book answer is 420 but I get over 600.

    Thank you,
  2. jcsd
  3. Feb 24, 2010 #2


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    Science Advisor
    Homework Helper

    I don't see that you've done anything wrong so far. How did you finally get to 'over 600'?
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