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Homework Help: Pole Vaulting Kinematics Problem

  1. Sep 15, 2013 #1
    1. The problem statement, all variables and given/known data
    A pole-vaulter leaves the ground with an upward speed of 9.5 m/s.
    (a) How fast is she going when she is 2.0 m above the launch point?
    (b) How long is required to reach this height?
    (c) Why are there two answers to (b)?

    3. The attempt at a solution

    Question A and B I don't have a problem with. I worked out A to be 7.1 m/s (2 sig digs) and B to be 0.2 seconds (2 sig digs).

    However it is question C I am not understanding. I feel tempted to write "because I can write the answer in seconds or I can write it in minutes". But I feel this is a silly answer, therefore I need help.
  2. jcsd
  3. Sep 15, 2013 #2


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    Gold Member

    When the pole vaulter goes up, she must come down.
  4. Sep 15, 2013 #3
    So there could be one answer that measures her going up and one answer that measures her going up then coming down?
  5. Sep 15, 2013 #4


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    Gold Member

    Yes, depending on what kinematic equation you use you will either get the two solutions automatically or not.
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