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Homework Help: Submarine and torpedo

  1. Oct 15, 2006 #1
    A submarine of mass 2.3 times 106 kg and initially at rest fires a torpedo of mass 260 kg. The torpedo has an initial speed of 100.9 m/s. What is the initial recoil speed of the submarine? Neglect the drag force of the water.

    My work:

    Pi=Pf
    Pi=0
    Pf= Mtorpedo * Vtorpedo - Msub * Vsub

    Vsub = (260kg * (100.9 m/s) ) / 2.3 x 10^6

    I get Vsub = .0114 m/s

    Why is this wrong?? Thanks
     
  2. jcsd
  3. Oct 15, 2006 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks OK to me. Why do you think it's wrong?
     
  4. Oct 15, 2006 #3
    Stupid online homework system, I had to take the answer out a few more decimal places.

    Thanks for your help Doc Al, appreciate it.
     
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