If this hand water pump was instead at the bottom of a well....

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Discussion Overview

The discussion revolves around the mechanics of a hand water pump, particularly the differences in force required to lift water from various depths, such as from a well versus a container. Participants explore concepts related to fluid dynamics and the forces involved in moving water through a pump mechanism.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants argue that the force required to lift water should be the same whether pulling or pushing, as the height of the water column remains constant.
  • One participant questions the force needed to pump water from the bottom of a well, suggesting that the weight of the water above the piston would increase the force required.
  • Another participant presents an analogy involving a straw to illustrate that the effort required to suck water from different sources does not depend on the amount of water above, but rather on the column of water being moved.
  • There is a discussion about whether sucking or pumping water is equivalent to pushing or lifting, with some asserting that the force exerted on the liquid column is what matters.

Areas of Agreement / Disagreement

Participants express differing views on the mechanics of lifting water, with no consensus reached on whether the force required changes based on the water source or depth.

Contextual Notes

Participants do not fully resolve the implications of weight and pressure in their arguments, leaving assumptions about the mechanics of fluid movement and the role of atmospheric pressure unaddressed.

RipleyGallegos
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Seems to me what matters is the force required to get the water up and I don't see why that would be any different whether you were pulling it up or pushing it up. The height of the water column is the same either way.
 
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phinds said:
Seems to me what matters is the force required to get the water up and I don't see why that would be any different whether you were pulling it up or pushing it up. The height of the water column is the same either way.

Okay Thank you! What if the little lever only pumped 1 gallon per stroke at like only 10lbs of pressure. & say his was a well with 500 gallons in it. From the top it seems there isn't much of any water weighing down on the piston so that the lever is very easy to push n pull.
If the piston is on the bottom doesn't it seem like we than would have 500 gallons weighing down on it? It seems to me that it would take much more force to pump that 1 gallon from the bottom. Hmm
 
Suppose you have a straw two feet long and you stick it 1.5' into a very tall glass and suck up the liquid in the glass. That takes a certain amount of force. Now stick the same straw 1.5' into a lake and suck up the lake water. I think you logic would say that the latter requires more effort but of course it doesn't. What matters is the column of water being moved.
 
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phinds said:
Suppose you have a straw two feet long and you stick it 1.5' into a very tall glass and suck up the liquid in the glass. That takes a certain amount of force. Now stick the same straw 1.5' into a lake and suck up the lake water. I think you logic would say that the latter requires more effort but of course it doesn't. What matters is the column of water being moved.

Wow that's a really great way of putting it! But do you think sucking or pumping up is equivalent to pushing or lifting up?
 
RipleyGallegos said:
Wow that's a really great way of putting it! But do you think sucking or pumping up is equivalent to pushing or lifting up?
Yes, if you are talking about exerting a force on a specific column of liquid. Again, all that matters is the amount of liquid being moved. If you are pushing up a 1cm diameter column of water it makes no difference whether that column is surrounded by a glass full of water or an ocean full of water.
 
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phinds said:
Yes, if you are talking about exerting a force on a specific column of liquid. Again, all that matters is the amount of liquid being moved. If you are pushing up a 1cm diameter column of water it makes no difference whether that column is surrounded by a glass full of water or an ocean full of water.

Thank you very much phinds!
 

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