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Homework Help: Communicating Vessels- how? (searched forum, didn't find it before)

  1. Feb 4, 2014 #1
    1. The problem statement, all variables and given/known data

    I don't know much about physics, I'm using-

    2. Relevant equations
    So say we got our 2 containers with a straight passage between them (they're cylinders for the sake of the question), and the right one has double the radius.

    So I'm assuming there are 2 forces pushing each other (in the passage), one from the weight of the right container, and one from the left.

    The right one has more mass (assuming they've got equal height of water which is basically what communicating vessels say). Wouldn't it be "pushing" the water in the passage with more force?

    If it does, does it cause a circular motion of water on the other side? Otherwise why doesn't it rise?

    3. The attempt at a solution

    As stated above I'm proposing the motion of water moving in a circular motion on the left container.

    As a side note, might be negating myself, but when I'm water pushes down other water (say in the right container, water is pressing the water under it, which is next to the passage), does it push the water to the sides?

    Thanks in advance.
    http://assets.overclock.net.s3.amazonaws.com/1/17/1721d4ed_vbattach152018.png here's a picture to help understand my question.
  2. jcsd
  3. Feb 4, 2014 #2


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    Let me check: Under 1) problem, there is no problem but a statement. Under 2) relevant equations there is a partial problem statement and a question and under 3) there is a proposal and a question.

    Suppose I want to help, what can you do to help me help you (except: get organized and use the template properly) ?
  4. Feb 6, 2014 #3
    Hello and thanks for the response, seems I can't edit the post.
    The question is in the title, I don't know any equations other than the one given, you'll have to forgive it being in the wrong place.

    My proposal does not include a question, it's a proposal that is phrased as one.
  5. Feb 6, 2014 #4


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    PF allows you do do a little editing for a while, then it fixates. You can add stuff in subsequent posts, though.

    So the question is more or less: what is the equilibrium condition if two vessels are connected by some means.
    Well, equilibrium means the water in the connection isn't moving. Water moves under pressure difference. The weight in the right vessel is bigger than in the left, but the bottom area is also bigger. So the force (mg) per area is the same (if the liquids are at he same levels). Pressure is only dependent on how deep you are. 0.5 m deep in the ocean is not different from 0.5 m deep in your bath (with some bath salt ;-) )

    That means that in de connection the forces from left and right vessel are equal and opposite: they cancel and ##\sum F=0##: no movement
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