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Question on a ball dropping( conservation of energy)

  1. Oct 18, 2014 #1
    1. The problem statement, all variables and given/known data

    A ball of mass 1 Kg is dropped from a height of 7m and rebounds to a height of 4.5m Calculate:
    its kinetic energy just before impact
    the initial rebound velocity of the ball and kinetic energy. Account for loss of kinetic energy on impact



    2. Relevant equations

    i am not sure of all the relevant equations i used pe=mgh and k.e=1/2mv^2

    3. The attempt at a solution
    I found the answer to a using the formula P.E.=mgh=1x10x7=70J
    K.E.=P.E.=70J
    I do not know how to find the second answer
     
  2. jcsd
  3. Oct 18, 2014 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Good.

    Use the same equation. (A different height, of course.)
     
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