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Homework Help: Ball launcehd off a Cliff

  1. Jan 28, 2010 #1
    1. The problem statement, all variables and given/known data

    Ok, you have a cliff with height h and you launch a ball off of it at speed v and angle [tex]\theta[/tex]. How long till it hit the ground?

    2. Relevant equations

    (1) Vsin([tex]\theta[/tex]) = V[tex]_{y}[/tex]
    (2) V[tex]_{f}[/tex] = V[tex]_{y}[/tex] + at
    (3) d = ((V[tex]_{i}[/tex] + V[tex]_{f}[/tex])/2)*t



    3. The attempt at a solution

    Ok, so what I did was take equation (2) and set V[tex]_{f}[/tex]= 0. This alllows me to solve for the time that it takes to reach peak. Multiply this result by 2 to get the time when the ball is back to the plane of the cliff. Then for the time down to the ground I used equation (3) and plugged in V[tex]_{f}[/tex]= [tex]\sqrt{V^{2}_{i}+2gh}[/tex] for V[tex]_{f}[/tex]. Then I solved for t.

    This lead to a result I feel looked to complicated for the question. Did I do this right?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jan 28, 2010 #2
    Ok, I don't know why all my subscripts look like superscripts in this but they do. All those i's and f's are for intial and final velocity.
     
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