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Projectile Motion ball is thrown upward

  1. Oct 13, 2014 #1
    1. The problem statement, all variables and given/known data
    A ball is thrown upward at an angle of 30° to the horizontal and lands on the top edge of a building that is 20 m away. The top edge is 5.0 m above the throwing point. How fast was the ball thrown?

    2. Relevant equations

    3. The attempt at a solution
    Im not sure what I am supposed to do considering there is no velocity given
  2. jcsd
  3. Oct 13, 2014 #2


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    Gold Member

    Well, the problem is asking for the initial velocity, so its very natural that the initial velocity is not given to you!!!

    Just take a look at the equations you have at hand and see which one has only one unknown, taking into account the data given in the problem.
  4. Oct 14, 2014 #3
    So the ledge coincides with the apex of the parabola
    You also need the value for g (gravitational acceleration)
    Youll be working on the vertical vector of the launch velocity first
  5. Oct 14, 2014 #4


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    Staff: Mentor

    Not necessarily. The projectile can land at the given spot after passing through its zenith.

  6. Oct 14, 2014 #5
    This assumption is not implied by the text and is not necessary.
  7. Oct 15, 2014 #6
    Beyond me, sorry.
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