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Homework Help: Inclined pendulum

  1. Nov 14, 2009 #1
    1. The problem statement, all variables and given/known data
    A train is travelling at 30m/s and decelerates and stops. During this process a passenger notices that a penduum is inclined by 10 degrees to the vertical. Estimate how far the train travels before coming to rest

    2. Relevant equations

    3. The attempt at a solution
    I have drawn a diagram of the pendulum hanging from a string with tension T at an incline of 10 degrees to the vertical. The tension will have two components
    Ty=Tcos(10)=mg and
    Tx will be the net horizontal force on the pendulum

    rearranging I got tan(10)=a/g

    then using v^2=u^2+2as
    =(0-30^2)/2gtan(10)=260.415m which seems a big too large
  2. jcsd
  3. Nov 16, 2009 #2


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    Homework Helper
    Gold Member

    I haven't checked your numbers, but your method looks fine. (And 260m doesn't seem like too large a stopping distance for a TRAIN to me:smile:)
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