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2D Kinematics

  1. Sep 12, 2013 #1
    Im sorry I just realized this is in the wrong subforum......

    1. The problem statement, all variables and given/known data

    Hello Everyone! Im new here and am having trouble with this webassign question. I was able to work out the answer to the first two but the last two are giving me trouble. Im not sure if this is right subforum to put this in, but I am in physics with calculus (Mechanics).

    A boy throws a stone horizontally from the top of a cliff of height h toward the ocean below. The stone strikes the ocean at distance d from the base of the cliff. In terms of h, d, and g, find expressions for the following.

    the time t at which the stone lands in the ocean

    the initial speed of the stone

    the speed of the stone immediately before it reaches the ocean

    the direction of the stone's velocity immediately before it reaches the ocean

    2. Relevant equations

    vf=vi+gt
    xf=xi+vi(t)+(g/2)(t^2)

    3. The attempt at a solution

    The answer I got for the first one was √(h/(g/2)) which was right

    The second one I got was √((d^2)/(h/(g/2))) which was also right

    For the third one I got vf=g(√(h/(g/2))) which I thought was right because vf for the x componet is 0 and the velocity is maximum at tf, however webassign is telling me im wrong.

    Thank you all for the help in advance!!!!
     
    Last edited: Sep 12, 2013
  2. jcsd
  3. Sep 13, 2013 #2

    lewando

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    Gold Member

    If you show your steps leading to your result, the mistake can be better identified.
     
  4. Sep 13, 2013 #3

    PhanthomJay

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    Gold Member

    Think about this a bit more....what is vf_x just before it hits the ocean?
     
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