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Homework Help: Momentum boat Question

  1. Nov 26, 2007 #1
    1. The problem statement, all variables and given/known data
    A 40 kg child and her 75 kg father simultaneously dive from a 100 kg boat that is initially motionless. The child dives horizontally toward the east with a speed of 2m/s, and the father dives toward the south with a speed of 1.5m/s at an angle of 37degrees above the horizontal. Determine the magnitude and direction of the velocity of the boat along th mater's surface immediately after their dives.

    I have no idea about the question, please help! thanks
  2. jcsd
  3. Nov 26, 2007 #2


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    Take the component of the man's momentum on the horizontal plane. Now the man's momentum and the child's momentum are perpendicular to each other. According to conservation of momentum the resultant of these two momentum should be the momentum of the boat.
  4. Nov 27, 2007 #3
    it's a collision so momentum is conserved, and initial speed of the whole system is 0. This is like a grenade exploding, the kinetic energy of the system should increase but the momentum is conserved.
    Add the vectors together and you should get 0, since the original momentum was 0.
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