Surface tension occurs due to the tendency of liquid molecules to favor their own kind. Surface tension is important in fluid multiphase systems typically at small length and velocity

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Water entering hole at a depth, surface tension

The following is the question that very commonly appears in all HS textbooks. A hollow sphere with a hole is taken to a depth of 40cm when the water starts entering the hole. if the surface tension of ...
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Surface tension and capillarity

The cause of surface tension is said to be asymmetry in the forces experienced by the molecules at the surface due to different interactions with air and liquid, but then the same argument also ...
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208 views

Why does tea rises in the pot but water don't?

I was wondering when I boil water in a pot it only shakes too much while boiling. But I could not figure out why tea rises in the pot when we boil it. it is also a liquid but it starts rising up till ...
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Why molecular forces do not obey inverse square law?

Most of the forces in physics obey inverse square law, but why molecular forces don't obey it.. Since molecular forces is also a form of electromagnetic force..
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Stripeless cleaning of windows

Cross post: http://chemistry.stackexchange.com/q/4377/22 Last week I was discussing with a friend how we thought the stripeless cleaning of windows is achieved when using a cleaner like Windex ...
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What causes insects to cast large shadows from where their feet are?

I recently stumbled upon this interesting image of a wasp, floating on water: Assuming this isn't photoshopped, I have a couple of questions: Why do you see its image like that (what's the ...
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Do gasses always mix because of their Gibbs free energy?

As far as I know there are no two gasses that don't mix (excluding demixing by gravitational effects). For me, as someone working with fluids and surface tensions a lot, this means that the surface ...
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834 views

How to measure a solid-solid surface energy?

Many techniques exist to measure the surface energy between a liquid and a liquid or a liquid and a gas (see e.g. the wiki page). Methods to measure the surface energy between a solid and a fluid are ...
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Why does string not wick down?

I regularly drink tea at work and I often reuse the tea bags (yes I know I'm a cheapskate). Yesterday afternoon I used a tea bag once and kept it in the cup in case I wanted another cup before I ...
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113 views

Contact angle of liquid drop on surface

How do you explain point 44 of the attached pdf document on surface tension? Here's the link. How is the direction of surface tension found out? (I know it tangential but in which direction along ...
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260 views

Satellite droplets in a breaking liquid jet

The famous example of a dripping faucet is an example of a Rayleigh-Plateau instability in which there is a certain jet radius below which perturbations on the surface will grow to break the jet into ...
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262 views

Depression of Water Surface by a Needle

Given a needle of mass $m$ modeled by a cylinder of length $l$ and radius $r$ placed on an infinitely large water surface, what is The maximum depression in the water surface; and The equation of ...
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182 views

Why do some liquid metals have anomalously-high surface tension/heat of vaporization ratios?

In a didactic article, Victor Weisskopf estimated the size of molecules in a liquid from measurements of their surface tension and heat of vaporization. If atoms are exceedingly small, then only a ...
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0answers
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Wrinkling paint - soluto/thermocapillarity - is it due to the primer or solvent [closed]

This is really a one-and-a-half part question. I know that when paint is mixed with a solvent or used with a primer, it sometimes wrinkles. As I understand, a key physical phenomena here is a ...
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5answers
273 views

How can the surface of a liquid exist if there are no attracting molecules above it?

Okay this is probably a stupid question but here goes: We know that molecules in a liquid are attracted from all the molecules around it so there is no net attraction. Well, then how do the ...
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184 views

Increment of surface tension with increase of temperature

What is the reason for the increase in surface tension of molten copper/cadmium with increase in temperature?
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How far can water rise above the edge of a glass?

When you fill a glass with water, water forms a concave meniscus with constant contact angle $\theta$ (typically $\theta=20^\circ$ for tap water): Once you reach the top of the glass, the water-air ...
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Does water have the same surface tension at same temperature but different volume?

I'm making an experiment and it is written in my older questions. Now, my question is - Does water have the same surface tension at same temperature but different volume?
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331 views

Lotus effect dust removal

I have found hundreds of papers describing the contact angle of water droplet sitting on hydrophobic surface and the change between Wenzel Regime and the Cassie-Baxter regime. Now, as I understand ...
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1answer
448 views

Calculational method for determining surface tensions from photograph of menisci?

How can I get from a photograph of a liquid surface to a value for the surface tension.
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214 views

Why does water make a liquid film?

Cut a narrow slit in a thin sheet of opaque material. Immerse the sheet in a liquid, such as water. After removing the sheet from the liquid, you will see a liquid film in the slit. The question is: ...
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727 views

Solving the Young-Laplace equation for arbitrary axisymmetric geometry

Say I have a non-ellipsoidal soap bubble and I want to numerically analyse the pressure in the inner lobe of this bubble here: The Young Laplace equation gives the pressure difference across a ...
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1answer
107 views

Beer bottle leftovers pour quickly only after waiting?

Why is it that after pouring a delicious beer from a bottle, I can hold it upside down for several seconds without reward, but if I wait a bit, the remainder presumably settles at the bottom and ...
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Physics behind Water drops during falling from a tap

what is physics behind Water drops during falling from a tap. water drop animation A drop or droplet is a small column of liquid, bounded completely or almost completely by free surfaces. Why Water ...
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245 views

Distinctive properties of liquids

The molecules are closely arranged in solids, loosely arranged in liquids and are free to move in gases... But, Why are liquids (especially water) exhibiting these distinctive properties such as ...
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1answer
519 views

Are coffee's properties different enough from water's to cause increased spillage while walking?

I recently found this article, which describes how... It just so happens that the human stride has almost exactly the right frequency to drive the natural oscillations of coffee, when the fluid is ...
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1answer
445 views

Change in appearance of liquid drop due to gravity

A liquid drop is spherical in shape due to surface tension. But why does it appear as a vertical line under the free-fall due to gravity? (E.g. During a rain - falling raindrop) Is there a specified ...
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506 views

Zigzag flow of water along a vertical glass window

I've observed this behavior many times. When it rains, the rainwater will form vertical channels along a glass window. The flow of water is mostly confined within these vertical channels and the ...
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2answers
443 views

Need help understanding dynamic and static contact angles

I've run into a conceptual road block. I'm coming to you guys because I think my adviser is getting annoyed with me. The concept involves a meniscus being pulled up a cylinder. I understand that ...
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1answer
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Why does water flow out of an upside-down bottle? (Rayleigh Taylor Instability)

I am currently reading the excellent book An Indispensable Truth: How Fusion Power Can Save the Planet by Francis F. Chen and I came across this explanation. The Rayleigh–Taylor Instability ...
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2answers
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'Applications' of surface tension [closed]

What are some common applications, uses, exploitations of the properties of surface tension? Here is what I mean. A water strider can walk on water, that is a consequence of surface tension. ...
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Why does a bullet bounce off water?

It is known that bullets can ricochet off a body of water. Is surface tension responsible for this or is this the same behavior we see when an asteroid ricochets off the atmosphere? I don't think ...
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1answer
166 views

What is “surface fluid adhesion energy”?

This is related to my previous question. Pardon me for asking so many questions recently. My physics knowledge is not that good, and some answers are hard to find. In the question in the link, I ...
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1answer
200 views

Is this formula for the energy of a configuration of 3 fluids physically reasonable?

I have studied for a couple of months now a mathematical model of the energy of a configuration of immiscible fluids situated in a fixed container such that the fluids fill the container. In other ...
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1answer
567 views

Contact angle formula still holds for liquid liquid interface?

I have seen in http://books.google.fr/books/about/Molecular_theory_of_capillarity.html?id=_ydSF_XUVeEC&redir_esc=y that there is a formula for the contact angle with a solid wall of a liquid-gas ...
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511 views

How specifically do emulsifiers work?

I'd like to understand better how emulsifiers prevent droplet coalescence. There must be something more they do than just lower the surface tension between the droplet and the ambient substance. I ...
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Amount of material required for a pressure tank

I read the answer for the question Why is a hot air balloon “stiff”? and thought something sounded ridiculous. My engineering requirement is that the walls be strong enough. Here $T$ will be the ...
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78 views

Lower state of energy for 'connected' molecules

Quote from Wikipedia: Another way to view surface tension is in terms of energy. A molecule in contact with a neighbor is in a lower state of energy than if it were alone (not in contact with a ...
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Collision frequency at surfaces

Collision frequency for particles in gases is well known, and collision theory is used to derive chemical reaction rates in gases, (and particles in liquid solutions as well). Using the mean velocity ...
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1answer
307 views

Causes of surface tension between two fluids

Suppose that we have two fluids $A$ and $B$ in a container $\Omega$, and we notice that $A,B$ do not mix. Can you pleas explain to me what is the cause of this property? What properties of the two ...
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Cooking pasta: why does adding a lid lead to overflow?

When cooking pasta, some organic foam usually forms on the surface of the boiling water and the situation can be kept under control by adjusting the heat (and/or adding some oil). Covering the pot ...
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2answers
417 views

Does the potential energy of fluid rising on a string change?

Lets say I have a glass of water at rest. Then I go and hang a string above the water (vertically), such as the end of the string is immersed in the water. Over time some of the water is going to ...
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2answers
202 views

At what size will self-gravitation contribute more to stability than surface tension?

The governments of Earth have embarked on an experiment to place a massive ball of water in orbit. (umm... special water that doesn't freeze) Imagine this to be a fluid with a given density, $\rho$ ...
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Surface Tension of a Liquid - When a liquid body is acclerating

As far as I understand it (which admittedly isn't very far), surface tension forces are made up by the tension-attractive forces of molecules at the liquid-gas/vacuum interface, such as those between ...
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Surface tension of solutions and mixtures

The inspiration for this question is over on cooking.stackexchange, asking more about actual measurements for commonly consumed liquids, but I'm interested more generally as well. What determines the ...
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2answers
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Hydrostatic friction: why do water droplets stay at rest on an inclined glass surface?

Tjis is a non-expert question on a (seemingly simple) text-book topic. The question is about "hydrostatic friction", defined as follows. Consider a drop of water resting on a flat surface. If the ...
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2answers
813 views

Bubble formation

I know that surface tension plays a key role in the formation of a bubble. I guess a bubble contains air inside it. Now how is it so that a soap bubble contains air both inside it and outside it? ...
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2answers
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Properties of liquid and air bubbles

What is/are the properties of a liquid (e.g. viscosity, surface tension) which is conducive to formation of stable bubbles floating in air (not the bubble inside the liquid)? E.g., if soap dissolved ...
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4answers
628 views

Can a “bowl” shaped liquid half-bubble be free-floating in the air?

Intent: Not looking to make-up something, I seek explanations which are possible to duplicate Description of Phenomenon: The halved side of the bubble would be horizontal to Earth's surface, and the ...
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1answer
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Dropping condition

Imagine opening a water tap in order to have a smooth and cylindrical outflow and then slowly decrease the flow by adjusting the knob. At a certain moment, the side profile of the flow will become ...