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Homework Help: Potential vs Kinetic Energy Help

  1. Oct 2, 2008 #1
    SO I am writing this fortran 95 program and the problem statement is the following:

    -Calculate the potential energy, kinetic energy, and total energy when a ball with an
    initial velocity of 0 is dropped from a 100 m building.



    KE = 1/2mv^2
    PE = mgh
    v = (2gh)^(1/2)


    The main issue I am having is the fact that the problem never gave a mass. I know
    that from the law of conservation of energy that I can set KE=PE and cancel out the
    masses. However this doesn't really get me anywhere. So far I have calculated all of
    my velocities that I need. But now I am stuck. Unless there is some super easy way to
    solve this and I just don't see it...

    mgh=(1/2)mv^2

    gh=(1/2)v^2 <=== This doesnt get me anywhere though
     
  2. jcsd
  3. Oct 2, 2008 #2
    [tex] mgh = \frac{1}{2}mv^{2} \rightarrow v = \sqrt{2gh} [/tex]

    Take the square root of both sides. =)
     
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