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Initial Velocity from Highest point and angle?

  1. Sep 13, 2011 #1
    Ok so having a little problem with this one and i feel like its easier than what i am seeing, but just not sure how i can get a V-initial from this (Replaced actual numbers with AAA and BBB because i am trying to recall how to do all this, hope ya'll dont mind variables to much lol)

    The highest barrier that a projectile can clear is AAA m, when the projectile is launched at an angle of BBB ° above the horizontal. What is the projectile's launch speed

    so i did use some trig and figured out the X-distance and the Hypot. but i wasn't given a time or acceleration....i've been looking through and rearranging some equations, and i feel like im just missing something obvious...help please

    Thank you, Litzkrieg
  2. jcsd
  3. Sep 13, 2011 #2


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    If you know the projectile's maximum height, you can easily figure out its initial vertical speed, since the projectile experiences constant acceleration in the vertical direction, and its speed reaches 0 at max height.

    If you know the vertical component of the initial velocity, and you know the angle, then you can find the horizontal component of the initial velocity.

    Once you know both components, you can find the total magnitude of the velocity.
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