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Homework Help: Finding maximum height

  1. Sep 11, 2009 #1
    1. The problem statement, all variables and given/known data

    An astronaut in his space suit can throw a ball a maximum distance dmax = 9 m on the surface of the earth.

    For a given speed of the ball, what angle to the horizontal q (in degrees) will yield the greatest range? 45 degrees

    If the ball is thrown at this same angle q, what speed will produce this greatest range (9 m) ? 9.3m/s

    How far can he throw the ball on a planet where g1 = 22 m/s2? 4.009

    What height will the ball reach on this "maximum range" trajectory? (on the planet where g1 = 22 m/s2)? I am having a problem with this one. I need help!

    2. Relevant equations

    v(y) = v(initial)*sin(angle)
    v(y) = v( y initial) + at
    y = y(initial) + 0.5(v(inital) + v)t

    3. The attempt at a solution

    v(y) = 9sin(45) = 6.57

    0 = 6.57 + 22(t)
    t = 0.298

    y = 0 + 0.5(6.57 + 0)*(0.298)
    y = 0.978

    Where did I go wrong? Did I need the vertial acceleration?

  2. jcsd
  3. Sep 11, 2009 #2


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    (y) = 9sin(45) = 6.57
    It should be
    (y) = 9.3sin(45)
  4. Sep 12, 2009 #3
    Ah yes I made a type, it should be 9.3. But I still am having trouble finding the maximum height...It seems that every approach I've tried it comes up wrong.
  5. Sep 12, 2009 #4


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    t = 0.2986
    = 0.299
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