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Homework Help: Projectile Motion Help

  1. May 23, 2010 #1
    How can one go about calculating the initial velocity of an object needed to travel a certain distance, starting from atop a given height.

    Variables known: height, angle, distance traveled, acceleration of gravity, mass of object
    Not known: initial and final velocity, time
     
  2. jcsd
  3. May 23, 2010 #2

    Andrew Mason

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    Use the http://hyperphysics.phy-astr.gsu.edu/hbase/traj.html#tra4".

    AM
     
    Last edited by a moderator: Apr 25, 2017
  4. May 24, 2010 #3
    These do not work since the launch point is not at the same level as the landing. And time is unknoen.
     
  5. May 24, 2010 #4

    rl.bhat

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    The range x = v*cosθ*t.

    So t = x/v*cosθ

    -y = v*sinθ*t - 0.5*g*t^2

    -y = v*sinθ*x/v*cosθ - 0.5*g*(x/v*cosθ)^2

    -y = x*tanθ - 0.5*g*x^2/v^2*cos^2(θ)

    Now simplify and solve for v.
     
  6. May 24, 2010 #5

    Andrew Mason

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    If you scroll down on the link I gave you, you will see how to analyse the problem.

    AM
     
  7. May 24, 2010 #6
    Thanks, it all makes sense now.
     
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