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Homework Help: Free fall motion from airplane

  1. Sep 14, 2012 #1
    1. The problem statement, all variables and given/known data

    A package is dropped at time t = 0 from a helicopter that is ascending steadily at a speed vi.
    What is the speed of the package in terms of V[itex]_{i}[/itex], g, and t?

    2. Relevant equations

    V (t) = V[itex]_{o}[/itex] + -9.8 t

    3. The attempt at a solution

    I thought it was the same as the normal equation for velocity such as stated above but with the different variables substituted for example:

    |V| = V[itex]_{i}[/itex] + gt

    except i got the answer wrong, then i tried putting a negative sign on the v[itex]_{i}[/itex] part but still got it wrong...help would be greatly appreciated.
  2. jcsd
  3. Sep 14, 2012 #2


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    You are close. Speed is |v(t)|. Try putting the magnitude bars around your expression for v(t).
  4. Sep 14, 2012 #3
    the magnitude bars are already there on the online hw, only the stuff to the right of the "=" sign is what i'm able to input....

    nvm i see what your saying....but there was another part of the question in which the plane was descending and asked the same question and i got it right without putting the '|' around v(t)
    Last edited: Sep 14, 2012
  5. Sep 15, 2012 #4


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    |V| = |Vi - gt|


    |V| = |gt - Vi|
  6. Sep 15, 2012 #5
    tried both but neither worked...i really think it is just the stupid website that i have to do the hw on but i'm all out of chances so doesn't matter now lol thanks for the suggestions though
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