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Homework Help: Basketball player kimetics

  1. Jan 18, 2010 #1
    1. The problem statement, all variables and given/known data

    A basketball player jumped straight up to grab a
    rebound. If she was in the air for 0.80 second,
    how high did she jump?
    (1) 0.50 m (3) 1.2 m
    (2) 0.78 m (4) 3.1 m

    2. Relevant equations

    d=Vit + 1/2at^2

    3. The attempt at a solution
    my calculations lead to '4' as my final answer, but the book tells me otherwise. There must be something I am missing. need help.
     
  2. jcsd
  3. Jan 18, 2010 #2

    rock.freak667

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    Re: Kinemtics

    The player is initially at rest and is only subjected to the acceleration of gravity.
     
  4. Jan 18, 2010 #3
    Re: Kinemtics

    Exactly!, thats i also assumed and if u work it out with that formula the answer turns out 3.1 m/s... but the book says my answer should be 1.2m/s.... doesn't make any sense to me at all.
     
  5. Jan 18, 2010 #4

    rock.freak667

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    Re: Kinemtics

    Well actually '2' seems to work out more, I don't know how your book for 1.2m.

    At the highest point, t=0.4s.
     
  6. Jan 18, 2010 #5
    Re: Kinemtics

    The problem is that the player's initial velocity is not zero, but unknown. I need to be on my way or I give the eq. you need.
     
  7. Jan 18, 2010 #6

    tiny-tim

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    Hi majormuss! :smile:

    She reached the top after 0.40 seconds, so the question is the same as 'how far does something fall in 0.40 seconds?' :wink:
     
  8. Jan 18, 2010 #7
    Re: Kinemtics

    thanks bro, that was very helpful...it turns the answer was really '2', I misread!.. thanx everyone.
     
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