Observing Ink Points in Water: What is the Motion?

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Discussion Overview

The discussion revolves around the motion of an ink drop in water, exploring the nature of this motion and the underlying physical principles, including diffusion and fluid dynamics. Participants consider whether the motion is linear or chaotic and how gravity may influence the behavior of the ink.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that the ink will diffuse in water, referencing diffusion as a key concept.
  • Others argue that fluid dynamics is relevant, particularly if the fluid were in motion, suggesting that the situation may be chaotic.
  • A participant mentions that for a drop of ink in still water, the diffusion equation could be applied, assuming uniformity in all directions.
  • There is a suggestion that gravity complicates the diffusion process, potentially leading to non-linear behavior.
  • Some participants express uncertainty about the OP's understanding of the problem, questioning whether they are looking for diffusion or fluid dynamics.
  • One participant introduces the concept of Brownian motion, suggesting it may explain the movement of ink molecules due to interactions with water molecules.
  • Another participant expresses confusion about the OP's clarity in presenting their question, indicating a perceived lack of understanding on the OP's part.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the motion of the ink is best described by diffusion, fluid dynamics, or a combination of both. Multiple competing views remain regarding the nature of the motion and the relevant physical principles.

Contextual Notes

There are limitations in the discussion regarding assumptions about the fluid state (still vs. moving) and the influence of gravity on the diffusion process. The complexity of the mathematical modeling is acknowledged but not resolved.

Who May Find This Useful

This discussion may be of interest to individuals exploring concepts in fluid dynamics, diffusion processes, or those curious about the behavior of substances in liquids.

Abofaisal2008
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Hello

I want know if i put ink point in water cup .. How i can describe ink point

motion ?? :rolleyes:
 
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The ink will diffuse. Look up 'diffusion'.
 
Or 'fluid dynamics'.
 
yes, i think diffusion . but i mean ink motion in water as liquied with liquied.

i think itsnt linear motion and i think its kind of chaos phenomena. Is that

right?
 
Particles diffuse in a liquid. But for a liquid mixing with a liquid it's fluid dynamics, as DaveC points out. Yes, it is rather chaotic. Fluid dynamics is difficult mathematically.
 
Fluid dynamics would only come into play if the fluid were moving. For a drop of ink in still water you should be able to apply the http://en.wikipedia.org/wiki/Diffusion_equation" . The simplesest solution would be if the ink drop were introduced into the middle of the liquid, rather then on the surface.

In the simple case you would use a spherical polar coordinate system and assume uniformity in all directions to get a solution in terms of only r, the radial component.
 
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Integral said:
In the simple case you would use a spherical polar coordinate system and assume uniformity in all directions to get a solution in terms of only r, the radial component.
Of course, gravity complicates things... first try without gravity:)
 
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DaveC426913 said:
Read the man's post:

"... ink motion in water as liquied with liquied. i think itsnt linear motion and i think its kind of chaos phenomena..."

It is obvious he is looking for fluid dynamics.

Perhaps you should try reading!
Abofaisal2008 said:
yes, i think diffusion

As for what you quoted, what the heck does that mean?
 
  • #10
Are we reading the same thread?

Integral said:
As for what you quoted, what the heck does that mean?
I quoted the OP's words about what he is looking for - not words that somebody else fed him.

When asked to elaborate what he is looking for, the OP's own words are about fluids in motion, and chaos.

Really, read the thread from post #1. Note what the OP is saying as opposed to what others are thinking he's saying.
 
  • #11
Yes, I am sure that the ink will diffuse it water.
 
  • #12
DaveC426913 said:
Are we reading the same thread?

I quoted the OP's words about what he is looking for - not words that somebody else fed him.

When asked to elaborate what he is looking for, the OP's own words are about fluids in motion, and chaos.

Really, read the thread from post #1. Note what the OP is saying as opposed to what others are thinking he's saying.

I guess not Dave cus I quoted the same post you did. I read the same lines you did only I see nonsense, clearly the OP does not know what he wants. I gave him a direct answer to that post. your posts are off topic and close to earning you a warning.

looks to me like YOU FED him fluid dynamics in post #3.

"WATER CUP" from post #1 does not imply a dynamic situation.

I will delete all further posts until we hear from the OP.
 
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  • #13
Is my problem not clear?

ok .. put ink in water glass and observe motion of ink its not linear motion and its like smoke motion

http://www.astrographics.com/GalleryPrints/Display/GP4293.jpg"

* I am sorry for my english lang:frown:
 
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  • #14
Thank you DaveC426913
 
  • #15
That could well be difusion acting unter the infuluence of gravity. I am not sure how gravity will interact with the diffusion equation but if it shows up as a non linear term, then you would see chaotic behavior.

As for fluid dymanics, there certianlly is not evidence of bulk motion of the water, if there were you would not see the delicate tentrils, they would lost in the currents, as the ink would simply follow the streamlines of the fluid.
 
  • #16
Abofaisal2008 said:
Is my problem not clear?

ok .. put ink in water glass and observe motion of ink its not linear motion and its like smoke motion

http://www.astrographics.com/GalleryPrints/Display/GP4293.jpg"

* I am sorry for my english lang:frown:

I think next time someone gives me a hard time when I make a point for a question to be presented in a clear manner, I will point to this thread.

The way that I have understood this is the evolution of a drop of ink in still water. This is a diffusion phenomenon, not a "fluid dynamics" problem.

While this is not an easy phenomenon to describe, I believe that what can be answered on here has been provided already.

Zz.
 
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  • #17
Hmm i think that if you are doing it simply then talking about Brownian motion , how the molecules vibrating in the water "hit" the ink molecules and how it transfers energy to the ink molecules and causes it to move (diffuse) would suffice
 
  • #18
i think that if you are doing it simply then talking about Brownian motion

Can you explain Browhian motion ? i think it for einstein .. Is that right?:bugeye:
 

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