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Homework Help: Very vague question about projectile launch angle

  1. Jan 26, 2006 #1
    The launching speed of a certain projectile is 5.2 times the speed it has at maximum height. What is the elevation angle at launching?

    Could someone just give me a starting point or a hint in the right direction?

    I know that the horizontal velocity doesn't decrease, and the vertical velocity is 0 at the maximum height. I can't put it together though; it seems like there isn't enough information given. How can you possibly tell by how much of a factor the speed is being affected by the vertical velocity, when you don't know the horizontal velocity?
  2. jcsd
  3. Jan 26, 2006 #2
    Maybe you can assume the magnitude [tex] V[/tex] of the lunching speed and find the relation between it and the horizontal velocity.

    Hint: use trigonometry
    Last edited: Jan 26, 2006
  4. Jan 26, 2006 #3


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    At the maximum height the y component of the velocity is zero, therefore the speed at maximum height is only the x-component of the motion. The x-component of the velocity stays the same throughout the motion.
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