Calculating Pressure Difference in a Vertical Water Pipe

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The discussion centers on calculating the pressure difference in a vertical water pipe extending 420 meters. The initial calculation incorrectly used a water density of 1 kg/m³ instead of the correct value of 1000 kg/m³. This error led to an incorrect pressure difference of 0.0407 atm. Upon correcting the density, the accurate pressure difference can be recalculated. The importance of using the correct density in fluid mechanics calculations is emphasized.
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Homework Statement



A vertical water pipe extends from the bottom to the top of the World Trade Center in the Big Apple (New York City), a distance of about 420 m. Calculate the difference in pressure in atm between the bottom and the top of the water pipe.

Homework Equations



p(y) = p - \rhogy

The Attempt at a Solution



\rhogy = (1 kg/m^{3}) (9.81m/s^{2}) (420m)
\rhogy = 4120.2 Pa
4120.2 Pa (1 atm / 101300 Pa) = .0407 atm

The answer above was wrong. Thanks for the help!
 
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The density of water isn't 1kg/m^3. It's 1000kg/m^3!
 
ohhh, that's what was wrong. thanks a lot! :smile:
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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