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Homework Help: Elastic Energy and Conservation of Energy

  1. Oct 15, 2008 #1
    1. The problem statement, all variables and given/known data

    A horizontal spring of force constant 12 N/m, is mounted at the edge of a lab bench to shoot marbles at targets on the floor 93.0cm below. A marble of mass 8.3 x 10^-3 kg is shot from the spring, which is initially compressed a distance of 4.0 cm. how far does the marble travel horizontally?

    i can see how i can calculate this, but im not sure what the energy statment is in this question

    originally i stated that

    Eelastic + Eg = Ek

    but that didnt work

    I tried Eelastic = Ek
    and that worked.

    but it dosent make sense why Eelastic + Eg = Ek dosent work.
    initially the ball is off on a table. so there should be gravitational potential energy...but why dosent it work with calculation?
  2. jcsd
  3. Oct 16, 2008 #2


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