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Homework Help: Horizontal Projectile Motion

  1. Sep 20, 2010 #1
    Zero Launch Angle Lab

    We used a spring loaded gun and shot a ball out of it.

    Here's the data:

    three trials:
    1.78 seconds
    1.34 seconds
    1.39 seconds

    the distance traveled was the same for each trial:
    2.98 meters

    the height is 1.04 m

    1. percent error on time.

    2. theoretical horizontal avg

    3. initial velocity

    I have no idea how to find what my teacher wants. In fact, no one in my class knows. I need help. Anything is appreciated.
  2. jcsd
  3. Sep 20, 2010 #2
    If you need me to provide any more information, let me know. I'm probably going to pull an all-nighter trying to figure this out. I think I should use the equation y=(-1/2)g(t^2). Any suggestions, advice, or guidance APPRECIATED! thank you.
  4. Sep 20, 2010 #3
    You need to calculate the motion in the horizontal and vertical directions. This is assuming you shot the projectile vertically from the height indicated.
    x = v0*t
    y = -(1/2)*g*t^2

    So you would use the vertical equation to calculate time:
    t = sqrt(2 * y / g)
    t = sqrt(2 * 2.98 / 9.8)

    Compare that value to the real time to get precent error on time.

    Then use the horizontal equation to calculate the initial velocity:
    v0 = x/t

    Here's a link to some physics calculators that helped me out for solving it.

    Hope that helps.
    Last edited by a moderator: Apr 25, 2017
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