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Finding Intial vertical and horizontal velocity with only range and max height known

  1. Sep 18, 2012 #1
    1. The problem statement, all variables and given/known data

    A basketball player is standing 9.5 m from the basket, which is at a height of 3.1m. she throws the ball from a initial height of 2m at an angle of 35 degrees above the horizontal. The ball goes through the basket. Determine intial velocity.

    PS Assume the max height of the parabola of the ball is 1.1 m.



    2. Relevant equations

    Dont know

    3. The attempt at a solution

    I took only half the parabola diagram and assumed v2 is 0 m/s

    Vert

    v1 = ?
    v2 = 0 m/s
    a = -9.8 m/s^2
    max height = 1.1 m

    I used the equation

    v2^2 = v1^2 + 2ad

    and got v1 as 4.64 m/s and from there on on I found initial velocity at an angle.

    BUT the textbook gives a different answer (11m/s) as the initial velocity at an angle.

    I can't figure out why I'm getting this wrong and my teacher sasys she will come back to me as she can't figure the mistake in mine... so help LOL
     
  2. jcsd
  3. Sep 18, 2012 #2

    lewando

    User Avatar
    Gold Member

    Re: Finding Intial vertical and horizontal velocity with only range and max height kn

    Not sure why you need to assume the max height of the parabola is 1.1m. It is already starting out at 2m.

    The textbook answer of 11m/s can be obtained by solving a system of 2 equations- one describing the motion in the y-axis and the other for the x-axis.
     
    Last edited: Sep 18, 2012
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