Which Water Tank Piston Requires More Force?

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    Head Pressure
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Discussion Overview

The discussion revolves around understanding the force required by pistons in two water tanks with different hose penetration heights. Participants explore concepts related to head pressure, static pressure, and the implications of fluid height on pressure exerted on the pistons.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant seeks clarification on head pressure and its implications for piston force in two similarly structured water tanks.
  • Another participant emphasizes the relationship between pressure head and the height of the fluid column, suggesting that greater height results in greater pressure at the base.
  • A third participant illustrates the concept of static pressure using an analogy with paper cups, indicating that a higher column of water leads to faster flow and greater pressure at the point of interest.
  • Some participants express issues with visual aids, such as diagrams, that are intended to clarify the discussion.

Areas of Agreement / Disagreement

There is no consensus on which piston requires more force, as participants are still exploring the implications of fluid height and pressure. Multiple viewpoints on the relationship between height and pressure exist, but no definitive conclusion has been reached.

Contextual Notes

Participants have not fully resolved the assumptions regarding the specific conditions affecting the pistons, such as the exact calculations of pressure based on the height of water above the pistons.

morfzcspls
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It may be a simple question to you but I need help understanding head pressure and I need to set things up to ask it.

Assume two 4 ft diameter by 25 ft tall water tanks, both are equally filled to 23 ft. Both tanks have chambers of the same diameter as the tank attached below them. Each chamber has a piston and has 2 ft of water above their pistons. Both chambers have a 4 inch diameter hose going from their chambers and into the tanks. On one of them, the other end of the hose penetrates the tank at 3 feet above the chamber. On the other the hose penetrates the tank at 22 ft above the chamber.

My question is, which piston will require more force or is there any difference. I would also appreciate any explanation that you want to include.
 
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morfzcspls said:
Assume two 4 ft diameter by 25 ft tall water tanks, both equally filled to 23 ft. Both tanks have chambers of the same diameter as the tank attached below them. Each chamber a piston and has 2 ft of water above their pistons. Both chambers have a 4 inch diameter hose going from their chambers and into the tanks. On one of them, the other end of the hose is penetrates the tank at 3 feet above the chamber. On the other the hose is penetrates the tank at 22 ft above the chamber.
Ahh.. Can you show a simple diagram? :biggrin:
 
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The pressure head depends on the density and elevation of liquid (or gas) above a given point by virtue of ρgΔh, where ρ is the mean fluid density, g is the acceleration of gravity, and Δh is the height of the fluid above the point of interest. The higher the column of water, the greater the pressure at the base or lowest point.

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
 
I have added a diagram called Undrstnd hd.png in hopes of clarifying this question.
 

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  • Undrsnd hd.jpg
    Undrsnd hd.jpg
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Big fat blank. Please try again. Always use the 'preview' button to check how your material displays before you post.
 
Sorry for the problem with the picture I attached previously. I’m having an issue with the latest update of DraftSight not exporting DWG files. Several of the formerly possible file types (.png, .tif, .wmf, .emf) create the file but they are not visible. So it seems the attached JPEG is visible.

Thanks
 

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  • phys question 01.jpg
    phys question 01.jpg
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static pressure head at a point inside a body of liquid is given by ρgh , as Astronuc Stated, where h is the height of the column of water above the point of interest, think of it this way, if you have two paper cups filled to the brim with water, and you put a hole in each cup, one near the top, and one near the bottom, the water will flow out faster from the hole near the bottom , because the h is higher, ie the column of water is higher, hence the static pressure is higher. similarly, your piston with the hose near the base of the tank will experience greater pressure
 

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