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Homework Help: Potential and Kinetic energy problem

  1. Mar 20, 2008 #1
    Potential and Kinetic energy problem!!

    1. The problem statement, all variables and given/known data
    im still stuck on the assignment: is the potential energy of a marble at the top of a ramp the same as the kinetic energy of the marble at the bottom of the ramp. I dont know the co-efficient of friction of wood but our teacher has told us keywords, they are: PREDICTIONS, measure the length the ball travels after its travelled down the ramp, FINAL VELOCITY and SEARCH DEEPER. so i have no idea what he's talking about

    2. Relevant equations

    3. The attempt at a solution

    we have measured height of the ramp and different times for the marble, can anyone tell me how i would measure final velocity? im really confused, and what does he mean by search deeper?
  2. jcsd
  3. Mar 20, 2008 #2
    Well the potential energy is calculated by how high the object is (Ep=mgh), and since kinetic is the object when it is in motion (Ek=1/2mv^2), you can safely say that if Ep=0, Ek=Ep@point 1.

    The thinking behind it is calculating the total mechanical energy, which is Em=Ep+Ek, so in theory the kinetic energy should equal what the Potential was at the top of the ramp. And since you "cannot destroy energy" there will be no energy lost, but as you know friction will come into play along with other sources that may cause the loss of energy from the object (such as sound. this may be what he's saying by search deeper)

    So somewhere to start, at the top of the ramp, you know that Ek=0, therefore Em=Ep
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