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Homework Help: Newton's third law Problem

  1. Feb 7, 2013 #1
    question is 29./ about bob and throwing his rock, I have found a./ (225N) easily enough it is b./ which i cannot figure out. Im assuming that it is a newtonian action-reaction pair and that the rock pushes back on bob at 225N as well, which would mean Bob's acceleration would be 3.0ms/s^2. But how do i found his take off speed (I'm asuming kinematics but not sure how with missing variables)??

    Answer is 0.2m/s which i cant understand??
  2. jcsd
  3. Feb 7, 2013 #2
    Could you post the complete question.
  4. Feb 7, 2013 #3
    hahhaha didnt even post the question, there you go

    Attached Files:

  5. Feb 7, 2013 #4
    The simplest way to do this is with conservation of momentum.
  6. Feb 7, 2013 #5
    thanks, didnt think of that
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