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Homework Help: Maximum Horizontal Distance

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

    Some students at Rice University have built their first
    gazilcher – a large slingshot (operated by five people
    at once, and capable of launching objects well over 100
    meters in distance) constructed from surgical tubing
    and a cafeteria silverware basket. They wish to launch
    a water balloon through a window on the first story of
    a dormitory. The window has a vertical height h relative
    to the ground where the gazilcher is activated. In
    order to avoid getting caught, the culprits wish to be
    as far away as possible. Furthermore, they always aim
    their gazilcher for its maximum range, R, which they
    have exactly measured. Show that the maximum horizontal
    distance between the gazilcher and the target
    window, neglecting air resistance, is given by

    2. Relevant equations

    d= R/2(1+ √(1-4h/R))

    3. The attempt at a solution

    i used the angle 90 because it was the maximum range/height regarding that they needed maximum length. I used the equation for Range to get the Height that they had. I seem to not understand how they got the 1-4h/r within a radical.
  2. jcsd
  3. Sep 11, 2010 #2
    Here's the way I did it
    1. We know that 45 degrees gives max height and max range.
    2. Using projectile motion equation y=xtanB-(1/2)gx^2(VocosB)^-2 set it equal to 0.
    3. Since max R=(Vo^2)/g solve for (Vo^2) and substitute.
    4. Solve for X after substituting and you're done.

    If you need any more help just let me know.
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