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Homework Help: Buoyant force

  1. Mar 19, 2016 #1
    1. The problem statement, all variables and given/known data
    why there is - sign in front of integral of (z2-z1)dA , is it a mistake ?

    2. Relevant equations


    3. The attempt at a solution
     

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  2. jcsd
  3. Mar 19, 2016 #2
    In your picture, they define the height of the volume element (a positive number) as z1-z2. This means that z1 must be the larger number. I'm guessing that they must be thinking of z=0 as the surface of the fluid, making z1 and z2 negative numbers....so they have the negative sign out front to make the force act in the positive z direction. Just a guess anyway.
     
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