Conceptual Question About Hydrostatic Forces

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Discussion Overview

The discussion revolves around the conceptual understanding of hydrostatic forces in a system involving a cubic container and a pipe filled with water. Participants explore how pressure is influenced by the height of the water column and the implications of varying the diameter of the pipe.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why the pressure at the bottom of the container remains the same even if the diameter of the pipe is significantly reduced, suggesting that only the height of the water affects pressure.
  • Another participant introduces a scenario involving a steel hollow sphere and a thin tube, questioning whether the pressure would change if the tube is filled with water, and expresses confusion about the relationship between added water mass and pressure exerted on the sphere.
  • A different participant asserts that pressure is defined as force per area, indicating that pressure remains constant with the same height of water, independent of the area of the pipe.
  • A later reply references Pascal's Vases and the hydrostatic paradox, suggesting that the pressure should remain unchanged regardless of the pipe's diameter.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between pipe diameter, water height, and pressure. There is no consensus on the implications of these factors, and the discussion remains unresolved.

Contextual Notes

Participants highlight the need for clarity on the assumptions regarding pressure calculations and the effects of varying dimensions in hydrostatic systems. The discussion does not resolve the underlying conceptual questions posed.

Who May Find This Useful

This discussion may be of interest to students and professionals in physics and engineering, particularly those exploring fluid mechanics and hydrostatics.

theLiminator
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Homework Statement


A 30-ft-high, 1-ft-diameter pipe is welded to the top of a cubic container (3ft x 3ft x 3ft). The
container and pipe are filled with water at 20°C. Determine the pressure forces on the bottom and sides of the container.

I already know the solution to this problem, but I don't get how it conceptually makes sense. It says that the pressure at the bottom would be equal to 33ft*specific weight of water. However, I don't get this concept. It basically means the amount of water on top makes a difference to the pressure at the bottom, only the height. My questions is, if you change the diameter of that pipe to something ridiculously small, such as 1 micron, why would the pressure at the bottom remain unchanged?
 
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Oh, another concept I don't get:

If we attached a steel hollow sphere with a very thin thickness to the bottom, and remove to top tube, the pressure would go down right? But imagine if you add an ultra thin, but really long tube to the top, and fill that tube with water, wouldn't it crush the sphere due to incredibly high pressure? To me this isn't intuitive if you end up only adding maybe 500g of water (when using an incredibly thin tube).
 
Aren't the units of pressure (force by area) like psi. So you'll have the same pressure with the same height of water because pressure is independent of the actual area.
You're just saying that this much force is acting per this area (which is a constant).
This makes sense to me, I hope its right and hope it helped.
 
theLiminator said:

My questions is, if you change the diameter of that pipe to something ridiculously small, such as 1 micron, why would the pressure at the bottom remain unchanged?


As far as I know it should be. Try to google and find something about Pascal's Vases or hydrostatic paradox.
 

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