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Momentum and kinetic energy

  1. Jan 5, 2015 #1
    "if kinetic energy of system of particles is zero, then linear momentum of that system of particles is zero but the reverse is not true. That is if linear momentum of a system of particles is zero, then the kinetic energy may not be zero"

    This is what I got from my text. Can you provide me with some examples because I am a bit confused. Can you provide some explanation?
    Is this true for angular momentum?
     
  2. jcsd
  3. Jan 5, 2015 #2

    Vanadium 50

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    Consider two particles with mass m, one with velocity +v and one with velocity -v.
     
  4. Jan 5, 2015 #3
    So momentum is zero and kinetic E is not zero. Can you give an example for kinetic energy zero and momentum non zero?
     
  5. Jan 5, 2015 #4
    KE = sum of 1/2 mv2. Can any of those terms be negative?
    Or, imagine covering the whole system with a curtain or box and treating it as one object of total mass M and velocity V.
    P=MV, while KE= 1/2MV2+ KE(within system, relative to the center of mass)
    If KE = 0, what does that imply? Assume masses are never negative.
     
  6. Jan 5, 2015 #5
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