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Homework Help: Conservation of Momentum of roller-skates

  1. Mar 23, 2010 #1
    1. The problem statement, all variables and given/known data
    Anthony and Sissy are participating in the "Roll-a-Rama" roller-skating dance championship. While 75kg Anthony roller-skates backwards at 3m/s, 60kg Sissy jumps into his arms with a velocity of 5m/s in the same direction.
    m1= 75kg
    v1= 3m/s
    m2= 60kg
    v2= 5m/s
    v' = ?

    2. Relevant equations

    The inelastic collision equation possibly?

    3. The attempt at a solution
    (75kg)(3m/s) + (60kg)(5m/s)= (75kg+60kg)x
    225kg*m/s + 300kg*m/s= 135kg(x)
    525kg*m/s = 135kg(x)
    (525kg*m/s)/135kg = x
    3.8m/s= x

    Is that correct?
  2. jcsd
  3. Mar 23, 2010 #2


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    Homework Helper

    Yes, it is inelastic collision and your calculation is correct, but take care of rounding. x=3.888... round it to 3.9 m/s.

  4. Mar 23, 2010 #3
    Thank you very much :)
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