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Perfectly inelastic collision

  1. Sep 26, 2009 #1
    1. The problem statement, all variables and given/known data
    Kevin has a mass of 84.2 kg and is skating with in-line skates. He sees his 23.2-kg younger brother up ahead standing on the sidewalk, with his back turned. Coming up from behind, he grabs his brother and rolls off at a speed of 1.74m/s. Ignoring friction, find Kevin's speed just before he grabbed his brother.

    2. Relevant equations
    V= d/t ?
    I have no idea how to solve this eqn!
    The only eqn i have for perfectly inelastic collision involves center of mass.

  2. jcsd
  3. Sep 26, 2009 #2


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    Science Advisor

    In an inelastic collision, kinetic energy is lost, but momentum is still conserved. Use conservation of momentum.
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