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Where does this kinematics equation come from?

  1. Jan 29, 2010 #1

    g= acceleration due to gravity (9.8m/s^2)
    t= time
    vox = initial velocity in the x direction

    Where does this equation come from?? someone told me to use this to help me solve one of my hw problems and it worked but i have never seen it before and am having a hard time to figure out where the components of the equation actually come from?

    could anyone help explain this equation to me?

    thank you
  2. jcsd
  3. Jan 29, 2010 #2

    Doc Al

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    Staff: Mentor

    This looks like a formula for calculating the angle below the horizontal that a projectile will be moving after time t after being released with a purely horizontal speed of V0x. It's just tanθ = Vy/Vx. Vy = at = gt.
  4. Jan 29, 2010 #3


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    Science Advisor
    Homework Helper

    Hi mybrohshi5! :smile:

    (have a theta: θ and try using the X2 tag just above the Reply box :wink:)

    If at time t, the angle is θ and the speed is v, then

    vsinθ = gt

    vcosθ = vx0,

    so tanθ = gt/vx0 :wink:
  5. Jan 29, 2010 #4
    thank you both! that makes complete sense now.
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