1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook