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Homework Help: Conservation of momentum of a raft

  1. Apr 4, 2005 #1

    i'm having trouble solving this problem....hopefully someone can at least get me started

    A raft of mass 180 kg carries two smimmers of mass 50 kg and 80 kg. The raft is initially floating at rest. The two swimmers simultaneously dive off opposite ends of the raft, each with a horizontal velocity of 3 m/s. With what velocity and in what direction does the raft start to move? (Note: there are three objects in the system)

    Thanks :smile:
  2. jcsd
  3. Apr 4, 2005 #2


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    HINT:The total momentum in the system is conserved.Note the relevance of the word "simultaneoulsy".That means that the swimmers transfer momentum to the boat only.

    A diagram of momentum vectors would help,too.

  4. Apr 4, 2005 #3
    The initial mass is 180+80+50. The final mass is 180kg, and was pushed by two swimmers of 130kg both at 3m/s. Take a stab at what will happen to the raft.
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