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admiral

Joined: 17 Sep 2005 Posts: 546
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Posted: Wed Jan 18, 2006 8:00 am Post subject: viscosity of fluidity? |
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Let's talk about it, how comes the surface tension of water? Has it something to do with viscosity? What is it generally?
I just want to start a peaceful scientific discussion. _________________ If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you" |
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Bob S.

Joined: 29 Apr 2004 Posts: 1767 Location: So. Cal
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Posted: Wed Jan 18, 2006 10:05 am Post subject: Re: viscosity of fluidity? |
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admiral wrote: |
Let's talk about it, how comes the surface tension of water? Has it something to do with viscosity? What is it generally? |
As I understand it, viscosity and surface tension are two different things. Viscosity has to do with the motion of a fluid's particles against each other. And that viscosity is in all three dimensions. But surface tension is acutally stronger since it takes a fluid particle's natural cohesive bonding and confines it to a two-dimensional surface. Or something like that. I'm not sure of the physics involved and how they are related, but both are quantifiable properties for engineering purposes. _________________ "It is impossible to speak in such a way that you cannot be misunderstood." -- Karl Popper |
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stellara

Joined: 02 Apr 2005 Posts: 583 Location: germany
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Posted: Wed Jan 18, 2006 12:11 pm Post subject: |
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hey I don't quite understand what you want to discuss.. Just the characteristica of water? ..
What I find very fascinating is that you can't compress it! Like you can compress air and then the pressure increases. It's just impossible..
yeah, Bob, what you say about viscosity sounds logically.
greets  _________________ Don't cry because it's over - smile because it happened!
MOKEY ROCKS!!! |
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admiral

Joined: 17 Sep 2005 Posts: 546
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Posted: Thu Jan 19, 2006 8:34 am Post subject: |
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I want to discuss the definition "viscosity".
My first idea about viscosity was the surface tension of e.g. water. However the higher the viscosity is, the slimier the fluidity will be, and I took two examples, petrolium and blood.
And however if you put a feather into a can of petrolium, it will sink faster than if you put it into a can of blood.
The surface tension describes the time delay until the feather falls into the fluidity, and the viscosity describes the sinking-velocity of the feather inside the water.
So, it must have to do anything with the surface tension? Or do you have a better explanation? _________________ If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you" |
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Bob S.

Joined: 29 Apr 2004 Posts: 1767 Location: So. Cal
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Posted: Thu Jan 19, 2006 3:31 pm Post subject: |
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admiral wrote: |
... I took two examples, petrolium and blood.
And however if you put a feather into a can of petrolium, it will sink faster than if you put it into a can of blood. |
A can of blood? Gah! Where do you get such a thing! Nevermind. I don't want to know.
Basically, blood is salt water with extra stuff thrown in, and water has a very high surface tension relative to its viscosity because of hydrogen bonding which gasoline does not have (or not as much of).
See here for a good explanation of surface tension and viscosity.
Water is a strange substance. Even though its molecules are smaller than those of gasoline, water's viscosity is about twice as strong. _________________ "It is impossible to speak in such a way that you cannot be misunderstood." -- Karl Popper |
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admiral

Joined: 17 Sep 2005 Posts: 546
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Posted: Fri Jan 20, 2006 6:13 am Post subject: |
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3rd paragraph, ll.9
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the viscosity of whole blood (cells plus plasma) is about 3 times
that of water |
from http://www.madsci.org/posts/archives/mar99/921961618.Me.r.html _________________ If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you" |
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admiral

Joined: 17 Sep 2005 Posts: 546
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Posted: Fri Jan 20, 2006 6:31 am Post subject: |
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And you can try to put some of your blood onto the table, if you compare it with water puored onto the table, you will see that water spreads faster.
Do you think this is a good prove? _________________ If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you" |
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Bob S.

Joined: 29 Apr 2004 Posts: 1767 Location: So. Cal
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Posted: Mon Jan 23, 2006 12:35 pm Post subject: |
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admiral wrote: |
And you can try to put some of your blood onto the table |
Gah! NO! Use your own blood!
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, if you compare it with water poured onto the table, you will see that water spreads faster.
Do you think this is a good prove? |
It proves that blood is thicker than water (which we know from the idiom ).
But really, how fast something spreads has as much if not more to do with the strength of the surface tension relative to the density of the liquid to hold back the liquid flow than with the viscosity of the fluid itself.
To measure just the viscosity, you need a way to eliminate the effects of surface tension. That should be covered somewhat in your engineering dynamics and fluid mechanics class. _________________ "It is impossible to speak in such a way that you cannot be misunderstood." -- Karl Popper |
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pugachevV
Joined: 16 Jan 2003 Posts: 2295
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Posted: Tue Jan 24, 2006 5:50 am Post subject: |
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We can say that viscosity is the resistance a material has to change in form. This property can be thought of as an internal friction.
Have fun. |
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admiral

Joined: 17 Sep 2005 Posts: 546
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Posted: Tue Jan 24, 2006 6:55 am Post subject: |
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ok, then surface tension has not very much to do with viscosity.
But then, how do you explain the difference between cementing motar and cementing water on a wall? Doesn't mortar have a higher viscosity rate? Isn't it's surface tension higher than water?
I just want to make this clear first, then I still have got a lot of questions... _________________ If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you" |
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pugachevV
Joined: 16 Jan 2003 Posts: 2295
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Posted: Thu Jan 26, 2006 5:35 pm Post subject: |
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Mortar is a powder that because of a hudraulic reaction becomes a solid.
I think its viscosity is not so important.
I think water has a viscosity of about 1 and may be the standard against which other fluids are measured.
I imagine if you want to do some research there's a lot of stuff available. |
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