Questions tagged [surface-tension]

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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Can tea leaves in a cup go to a kettle when water is pouring from that kettle?

I remember I have seen this happening before. But I am not sure why this will happens and have not taken any video. Any explanation are welcome.
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How does a sponge absorb water?

I am studying for YIPT questions. I want to know what are the parameters that help sponge to absorb liquid ?
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In nature, (generally) when liquid molecules lies on a solid surface which model does it came close with?

In nature, (generally) when liquid molecules lies on a solid surface which model does it came close with? {Does water molecules lies on solid interface with air pocket or without air pocket?} Cassie-...
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Hydrophobic surfaces and free fall

Does a hydrophobic surface, like Teflon or an "oily" plastic entirely repel water droplets when there is no force (such as gravity) forcing the surfaces together - or is there still some ...
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More details on surface tension and contact angle

I am a high school student and I am very confused in surface tension , In some books it is written that contact angle is formed because the surface of a liquid can't hold tangential stress so the ...
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Big confusion in surface tension

I am a high school student and I am very confused in the concept of surface tension and capillary rise phenomenon, my school level textbooks is very ambiguous about it they first tell you that the ...
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Surface energy in a solid cylinder [closed]

I have been trying this for over an hour and I still can't proceed: $$F = 2 \pi RT$$ $$W = F(\text{displacement})$$ $$W = 2 \pi R (\text{displacement})$$ $$W = 2 \pi R \Delta x \ \ \ \ \text{or} \ \ \ ...
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Stainless Steel in Kitchen Dishwasher Doesn't Dry

I find that stainless steel tools, especially the shiny ones, stay wet after the (no heat) dry cycle while ceramic plates are dry. The water beads on the shiny surfaces but perhaps less on rougher ...
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How does rubbing soap on wet skin produce foam, and does it really enhance cleaning?

We tend to rub soap after applying it to the skin. I found it interesting that the mere act of sliding our hands on the wet skin surface produces millions of air bubbles in the liquid, that later ...
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Does soap clean grease because it lowers surface tension? Or are these things independent?

Have you noticed how much easier it is to clean dirty, greasy hands or plates once you add soap to the water? By reducing the surface tension of water, soaps and detergents allow it to mix with oil ...
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Can mycelles of soap form without grease/oil in the middle?

Does soap form mycelles even if there is no grease in the water, like the image below? (Is it even possible to form mycelles without grease/oil in the middle)? Or do soap molecules stand on their own ...
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Laplace pressure in a bubble or film of liquid

Apparently, Laplace pressure in a bubble or film of liquid is simply the double of what it would be if it was a solid shape (a drop of water, for example). It makes sense because a bubble or film of ...
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Which are the radii of curvature in the Laplace Pressure formula?

Laplace pressure is given by $$\Delta p=\gamma \left(\frac{1}{R}+\frac{1}{R'}\right)$$ where $R$ and $R'$ are the radii of the curvature of the surface. Using the following diagram There are at least ...
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How does surface tension prevent a pin from sinking?

Please explain simply how surface tension in water which as far as I understand is a force pulling the water molecules at the surface towards each other horizontally so how does that prevent a ...
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Surface tension and capillary rise intution

I am high school student I am very confused in "surface tension", My confusion is that: 1) In this image I have shown that, In some books the reason for this shape of meniscus is explained ...
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What will the excess pressure of a water drop on a table be?

I'm aware of the formula for excess pressure of a spherical drop given by :$$\frac{2S}{R}$$ Where $R$ is the radius of the drop. But what if the drop was on the floor? Using the formula for excess ...
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Equilibrium Condition For Kelvin's Equation regarding “Equilibrium Vapour Pressure and Curvature of Drops”

This is regarding the Correction due to 'Curvature of the drop' made by Lord Kelvin to the Clausius-Clapeyron Equation. So, the idea is that, during large scale nucleation of water vapour into cloud ...
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When surfaces are smooth enough there is an effect called 'wringing' where they essentially form a bond, why does this occur?

I have seen two answers to why surfaces 'wring', ie stick together when below a specific level of roughness. This includes two general answers. The first is that they are acting like a suction cup, ...
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Why did water not drip form this small bottle?

I will explain what I have done and my observations. I took this bottle and added water into it. 1st time , 25 percent , then 75 percent and then 100 percent of water was filled in the bottle. Yes , ...
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Hand dipped in water and surface tension

If we dip our fore finger in water and we try to pull it out we notice that our forefinger sort of 'drags' the water along with it(see pic).My textbook says its because of surface tension and leaves ...
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Surface tension Numerical problem [closed]

A needle of length 5 cm can just rest on the surface of water of surface tension 0.073 N/m. Find the vertical force required to detach this floating needle from the surface of water. In this problem ...
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Is “wetting” of e.g. a hydrophilic surface by water the same thing as “adsorption” is with a gas?

Some substances are "pilic" (or polar) to another, some are "phobic", so they form droplets in liquid phase or on a surface. Even liquids "phobic" to a substance can be ...
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Microscopic turbulence in water

In the surface of water, the molecules are more tightly bonded than the bulk( and surface tension works ). But i have read that microscopic turbulence occurs in water surface. So does a molecule ...
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How does surface tension work?

If surface tension acts tangential to the surface, then how does a water drop shrink or compress inward?
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Drops are not spherical? [closed]

Surface tension tells us drops are spherical but dew drops or drops large ammount of big substance really fallapart or are not mainly a most perfect sphere. Is there hold the following and what is ...
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Calculating the tension in a string in a soap film

There is a horizontal film of soap solution. On it, a thread is placed in the form of a loop. The film is punctured inside the loop and the thread becomes a circular loop of radius $R$. If the surface ...
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Fluid static, splash of a water drop

I have the following question: A spherical water drop (wd1) of diameter D=1mm fall on a hydrophobic surface and divide into 8 identical spherical water drop (wd8 x 8), we have gamma (surface tension ...
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Adsorption of a $\rm H$ on a silicon(111) surface

Adsorption of $\rm H$ on $\rm Si$ is an activated process. I have measured Data: Sticking Coefficient as a function of Temperature $T$. How can I determine the activation Energy of the adsorption?
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Why can't capillary tubes overflow due to this reason? [duplicate]

It is known that raises to a certain height based on the parameters of surface tension, the radius of the tube, etc. Given by the formula $$h=\frac{2S\cos \theta}{\rho Rg}$$ When the capillary tube is ...
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Where does the energy go when two drops combine?

Recently been studying fluid mechanics and I have a query in context with surface energy. I am aware that energy is decreased when two drops combine, But not aware of where that energy goes. Does the ...
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Why powder of a metal doesn't form the solid metal again if molecular bond is so strong?

This might seem like a stupid question but please bear with me. I've always studied and read that the molecules at the surface have higher energy than those at the interior and the explanation is also ...
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How does a capillary pressure drop affect evaporation?

Normally phase changes are said to occur at a constant pressure, but in situations with a capillary pressure drop (like a heat pipe as shown in the picture below) there is a difference in pressure ...
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Role of Liquid gas interface in contact angle

In the diagram below, we see the three forces mentioned in the Young’s equation for contact angle. From the data book, we have Surface tension of water = 0.0727 N/m. Supposing that, the liquid in the ...
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Is there any pair of substance which has a negative surface tension?

I assume that positive surface tension for the interface between two substance implies that the molecules at the boundary are more "comfortable" - their energy is lower when surrounded by ...
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I have a container completely filled with water, I add copper coins, how much can the water level rise before it spills? [duplicate]

My question is, how can I calculate the total volume such that once reached, the surface tension and cohesion are insufficient to keep the water stuck to the glass? I mean when we add objects to the ...
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Why poke straw in center of sealed Boba cup? Why hit center of wooden barrel? [closed]

So I'm curious to know why, so very naturally, I have been poking my thick straw at the center of the seal of Boba cup. Why not the side, nearer to the brim where the plastic is not so stretchy? ...
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Surface tension on a film

Why don't the surface tension of the film of soap solution ( or any other liquid) increases or decreases when we increase the area of the film manually by applying a force ?? Isn't it analogous to the ...
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Why do we consider only liquid-air surface forces in capillary rise?

Consider this diagram from wikipedia. Now the diagram clearly depicts forces due to three interfaces. But in the derivation of capillary rise, we only consider the force due to Surface Tension of the ...
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Surface tension in a water drop

Consider the above image This is a pretty standard diagram but it makes no sense to me. I have some questions regarding it. Why are we taking surface tension of air-solid interface into consideration ...
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Free Body Diagram of Capillary Rise

I found have found several diagrams for capillary rise and they often display different forces. What is shown in one diagram may not be covered in the other. Can someone provide me with the free body ...
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Why is surface tension represented as forces at triple line? And why are they balanced horizontally only?

I thought that direction of surface tension is along the tangent to the surface which is best explained by this diagram which I found this diagram in Wikipedia But recently I saw in a book the ...
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Surface Tension: The line integral, the surface integral… and something in between?

Surface Tension as a Line Integral I have seen the surface tension force defined by multiple sources as the following line integral over the contact curve C (with trivial differences in notation among ...
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Defying gravity with vertical shaking?

I saw this video on levitating a denser liquid on less dense air by vertical shaking. But I couldn't understand some points in the video. Particularly: How did the liquid levitate? I think it's ...
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Columns of liquid on top of gas, when and why does gas bubble up through the liquid?

I have a long straw ("small" diameter tube of constant cross-section) hanging vertically above me. The straw is filled with liquid (water). I blow a finite volume of air (gas) into the lower ...
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Surface energy versus surface tension and contact angles

I am hoping to measure the surface tension between two fluids (salt water and isopropyl alcohol), by measuring the appropriate contact angles, and applying Young's equation: https://en.wikipedia.org/...
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Contact Angle vs Wetting Angle

On this site, among others, the angle used in determination of the surface tension forces on a solid object suspended in a liquid is referred to as "the contact angle". ($\theta$ in this ...
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Laplace pressure

I'm quite confused with Laplace pressure. I know the formula is (at least considering a spherical surface) $\Delta P = P_{in}-P_{out} = \frac{4\sigma}{d}$. What exactly is the surface you have to ...
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Air bubble of any shape in a viscid liquid

I am wondering about the existence of a function\action that would move the box so that the air bubble would take a given shape. Consider a subset of spaces $\Omega\subset \mathbb{R}^3$ maybe for a ...
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How is surface tension of the de-ionized water ( pure water ) decreased with the increase in the concentration of NaCl?

Can anyone help me with the theory of surface tension? My physics experiment is related to the surface tension and concentration of NaCl. I am confused about my Hypothesis. On the internet, I found ...
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Smaller droplets == smaller surface tension?

When applying soap liquid on the inner surface of swim goggles, the surface tension of the water decreases and small droplets of water on the surface won't form, therefore the fog won't form. In this ...

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