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Homework Help: Archimedes principle concepts

  1. Oct 18, 2007 #1
    1. The problem statement, all variables and given/known data
    A fisherman and his young nephew are in a boat on a small pond. Both are wearing life jackets. The nephew is holding a large helium filled balloon by a string. Consider each action below independently and indicate whether the level of the water in the pond, Rises, Falls, is Unchanged or Cannot tell.

    The nephew pops the helium balloon.
    The fisherman lowers the anchor and it hangs one foot above the bottom of the pond.
    The nephew gets in the water, looses his grip on the string, letting the balloon escape upwards.
    The fisherman knocks the tackle box overboard and it sinks to the bottom.
    The fisherman lowers himself in the water and floats on his back.
    The fisherman fills a glass with water from the pond and drinks it.

    2. Relevant equations
    Archimedes principle: buoyant force of a floating object is equal to the weight of the displaced fluid

    3. The attempt at a solution
    This is my question: How does the volume of fluid displaced by a body which `floats' differ from that for a body which sinks? I have no idea
    Last edited: Oct 18, 2007
  2. jcsd
  3. Oct 18, 2007 #2
    i really need help its urgent
  4. Oct 18, 2007 #3
    3. if a body is only floating on the surface, it is not displacing anything. it might as well not be there. if the body sinks down into the fluid, then the fluid basically has a big hole in it filled by this body and the fluid is 'displaced.'
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