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Homework Help: Potential energy

  1. Jul 14, 2004 #1
    This maybe an easy question for you, but for me im having trouble. Im working on 2D projectile motion and i need an equation to work out the inital velocity when i have the PE.
  2. jcsd
  3. Jul 14, 2004 #2
    Where are you stuck?

    The potential energy at a verticle height y above the datum is equal to mgy. The kinetic energy is (1/2)*m*v^2. If you want, you can use the following expression for y

    y = y_{0} + (V_{0}\sin \theta)t - \frac{1}{2}gt^{2}

    and substitute it into U = mgy and solve for [tex]V_{0}[/tex], the initial velocity.
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