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Homework Help: Projectile for a game

  1. Mar 8, 2005 #1
    I'm writing a video game. For the AI i need to be able to calculate the proper initial velocity for a given angle to hit a target a certain x,y distance away. I don't want to use time in the formula. Does any one know a formula for doing this? I found something about a "gunnery law" that looked similar to what i needed, but i couldn't find the formula. Any help would be appreciated since i'm a programmer and not much of a physics person. Thanks.
  2. jcsd
  3. Mar 8, 2005 #2

    Andrew Mason

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    If the target is at the same height as the launch, you can use:

    [tex]y= vsin\theta t - \frac{1}{2}gt^2[/tex]

    where: [tex]t = \frac{x}{vcos\theta}[/tex]

    If x = R (range) and y = 0, you have:

    [tex]vRtan\theta = \frac{gR^2}{v^2cos^2\theta}[/tex]

    [tex]v^3= \frac{gR}{tan\theta cos^2\theta}[/tex]

    [tex]v = \sqrt[3]{\frac{gR}{sin\theta cos\theta}}[/tex]

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