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Homework Help: Time Dilation/Length Contraction Question?

  1. Jan 19, 2014 #1
    1. The problem statement, all variables and given/known data
    A meter stick moves parallel to its length with speed v = 0.6c relative to you.

    a. Compute the length of the stick measured by you.
    b. How long does it take for the stick to pass you?

    2. Relevant equations

    t = to
    L = Lo

    3. The attempt at a solution

    Part a was easy enough, simply using 1m for Lo and v = 0.6c to get a contracted length of 0.8m.

    Part b, perhaps I'm overcomplicating things, but is it as simple as using the proper time as to = d/r = 1/0.6c and then using the time dilation formula?

    Or instead is it simply the contracted length divided by the speed?
  2. jcsd
  3. Jan 19, 2014 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    You are over complicating things.
    How would you normally work out how fast something is going to pass you?
    You take it's length, as measured by you, divided by it's speed.
    Which would be the last one.

    The length is only contracted or different when compared with some other observer's measurement.
    Everything involving only stuff you measure works the same as normal.
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