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Explosion with two Ice Skaters

  1. Mar 22, 2012 #1
    1. The problem statement, all variables and given/known data

    Two ice skaters stand at rest in the center of an ice rink. When they push off one another, the 60 kg skater acquires a speed of .61 m/s. If the speed of the other skater is .8m/s what is this skater's mass?

    2. Relevant equations

    explosion- pi=pf

    3. The attempt at a solution

    1/2m1v1^2=m2v2^2
    1/2(60)(.61^2)=m2(.8^2)
    11.16=m2(.64)
    m2=17.43 but it said this was wrong

    but then i got a really big number which doesn't seem right
     
  2. jcsd
  3. Mar 22, 2012 #2

    gneill

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    Staff: Mentor

    Recheck your formulas. What's the formula for the momentum of a moving body?
     
  4. Mar 22, 2012 #3
    p=mv?
     
  5. Mar 22, 2012 #4

    gneill

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    Staff: Mentor

    Is that a guess?
     
  6. Mar 22, 2012 #5
    so do i do m1v1=m2v2 instead of squaring the velocities
     
  7. Mar 22, 2012 #6
    got it! thanks
     
  8. Mar 22, 2012 #7

    BruceW

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    Homework Helper

    yes, that's right man. Its simply conservation of momentum.
     
  9. Mar 22, 2012 #8

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    There is NO "conservation of energy" (which is what you were trying to use first) because the "explosion" (push) adds energy to the system.
     
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