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Homework Help: Conceptual momentum and work questions

  1. May 20, 2010 #1
    1. The problem statement, all variables and given/known data

    1.) does a ball thrown upward lose momentum as it rises? explain.

    2.)a duck walks along a long thin raft in the water. what does the raft try to do? what hinders this action?

    3.)a golfball and a football have the same kinetic energy, which ball has the greatest momentum?

    2. Relevant equations

    3. The attempt at a solution
    1.) the decreasing velocity would temporarily change the momentum but ultimately the final momentum should equal the initial momentum.

    .)The raft trys to to shoot out and tip as the duck walks not sure what else.

    3.) the more massive football has the greater momentum.
  2. jcsd
  3. May 20, 2010 #2
    The ball's velocity certainly decreases when it is thrown up. How is velocity related to momentum?

    The problem is saying the raft is long which means its very large compared to the duck. It will most likely not slip out from under him if he walks along it. Now that being said, what does the raft try to do when the duck walks along it? If he takes one step forward, which way is he pushing on the raft? Seeing how things can move about very easily in water what do you think happens to the raft as he keeps walking forward along the raft? What small force could be countering this effect?

    Number 3 you got down.
  4. May 20, 2010 #3


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    But did you just guess this, or do you have a justification?
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