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Homework Help: Linear momentum handball problem

  1. Oct 9, 2008 #1
    1. The problem statement, all variables and given/known data
    A handball of mass 0.10 kg, traveling horizontally at 30 m/s, strikes a wall and rebounds at 24 m/s. What is the change in the momentum of the ball?

    2. Relevant equations

    change in momentum = mv2 - mv1

    3. The attempt at a solution
    Do you take 24 as negative or positive? If you take it as neative you get -2.4-3=-5.4 if you take it as positive you get 2.4-3= -.60
    both answers given in the problem are either positive 5.4 or positive 6.0. Thanks for your help
  2. jcsd
  3. Oct 9, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    If you take the 30 m/s velocity as positive, then you'd better take the 24 m/s as negative since it's going in the opposite direction. For the final answer they just want the magnitude of the change in momentum, which is always positive.
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