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Homework Help: Fluid pressure physics homework

  1. Sep 14, 2008 #1
    A 0.800 m-diameter vat of liquid is 2.70 m deep. The pressure at the bottom of the vat is 1.20 atm.

    What is the mass of the liquid in the vat?
  2. jcsd
  3. Sep 15, 2008 #2


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    Welcome to PF!

    Hi jason_r! Welcome to PF! :smile:

    Show us what you've tried, and where you're stuck, and then we'll know how to help. :smile:

    Hint: find the density first.
  4. Sep 16, 2008 #3
    Re: Welcome to PF!

    so far i have :

    PA=P_oA +mg
    (1215600)(pi*(0.4)^2)= (1.013x10^5)(pi(0.4)^2) + 9.8m
    m=1.04 x 10^4kg

    I need confirmation on the answer and if im doing this right
    cause i dont have a key or anything
  5. Sep 17, 2008 #4


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    Yes, that's fine:

    (I haven't checked your value for 1 atm … and I'm assuming you meant 10^6, so that it matches the 1215600)

    You've used a force equation … force on the bottom minus force on the top = weight … P-A - P+A = mg.

    You could also have use the pressure equation (that's the one I'd have used): P- - P+ = rho gh.

    But they both give the same result, and they're both fine. :smile:
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