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A couple of questions

  1. Oct 26, 2006 #1
    I have no idea how to do this first one

    1. Youre coasting with a friend on a sled, going a constant velocity, having a momentum of +120kg m/s when suddenly your friend bails off the sled. Assuming there are no net external forces acting on the system which of the following gives a correct possibility for the final momenta for first your friend, then you and the sled?

    a) -50 kg m/s, +170 kg m/s
    b) -50 kg m/s, +120kg m/s
    c) -50 kg m/s, -70 kg m/s
    d) +70 kg m/s, -50 kg m/s
    e) +120 kg m/s, -50 kg m/s


    my other question: Is momentum conserved in both elastic and inelastic collisions or only elastic?
     
  2. jcsd
  3. Oct 26, 2006 #2

    arildno

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    Counter-question:
    If a system is not experiencing any EXTERNAL forces, what can you say about the system's momentum?
     
  4. Oct 26, 2006 #3
    It's constant right
     
  5. Oct 26, 2006 #4
    This therefore means that the answer has to be B right? Because therefore the momentum for the sled is the same or am I wrong?
     
  6. Oct 26, 2006 #5

    arildno

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    What system is NOT experiencing external forces in this cases?

    Is it:
    i) You
    ii) You+sled
    iii) Sled
    iv) Sled+friend
    vii) Friend+you
    viii) Friend
    ix) You+Friend+Sled
     
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