# 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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### Surface tension and Speed of capillary action

I have read that the height of meniscus in a capillary is directly proportionate to liquid-air surface tension. That left me wondering, is the speed at which capillary action occurs also ...
1answer
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### How can I reduce the surface tension to achieve realistic 1:43.5 scale waves etc

I want to achieve realistic flowing water instead of using polymers which produce static water. Ideally using a small wave making device to represent the sea.
2answers
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### How to avoid water tension in a hose?

I am doing a project in which I have to flow water between two containers, which are connected at the bottom by a 1/4" hose. Remarkably, the surface water tension is such that water does not flow ...
1answer
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### Increase the surface tension of polypropylene

I'm working on a project and I need to increase the surface energy of polypropylene. I want you to tell me a way in order to increase surface_energy of polypropylene ?
2answers
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### Could situation where water does not pour out of a bottle change if different liquid is used [duplicate]

I was washing the dishes and came across a situation that was counterintuitive (at least from my perspective). The situation consisted of a bowl of water and a filled bottle of water. When I dip only ...
0answers
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### What is the physical meaning of “critical crack length”?

There are two equations that are primarily used in context of the fracture stress one with $\sqrt{\frac{\gamma E}{a_0}}$and the other with $\sqrt{\frac{2\gamma E}{\pi C}}$.I do not understand which ...
1answer
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### Surface Tension of Floating Object

I was reading this thesis about surface tension and its role in floating bodies. I couldn't quite understand at page 10 how the author applied the 2D divergence theorem outside the region bounded by ...
1answer
66 views

### What determines whether liquid droplets will combine or push into each other?

In trying to understand some fluid-dynamic principles, I am trying to discern between a couple water droplet interactions. This droplet video demonstrates the scenarios properly, but unfortunately ...
2answers
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### Why Air bubble are always sphere in shape? [duplicate]

Everyone of us had noticed air bubbles once in his life. They are Sphere in shape. But I want to know why the are sphere in shape, instead of any other shape.
0answers
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### Soap film bounded by a circular wire

If a soap film is bounded by two parallel circular wires, then the equation of its surface of the minimal area is $$r=c\cosh(z/c)$$ where $c$ is a constant and $r=\sqrt{x^2+y^2}$. This can be ...
1answer
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### Fluid pressure in Neumann's triangle for triple junctions

Consider a point of contact where three fluid phases meet. The Neumann's triangle rule for this case is usually written as, \begin{equation} \frac{\sigma_{\alpha\beta}}{\sin \gamma} = \frac{\sigma_{\...
1answer
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### Does water have a minimal thickness because of van der waals force?

I have read this question: The thickness of a puddled sheet of water https://en.wikipedia.org/wiki/Surface_tension#Puddles_on_a_surface The liquid mass flattens out because that brings as ...
1answer
59 views

### How do I measure pressure inside a water balloon?

I have fill a ballon with water. The balloon becomes big for its elasticity. So a potential energy is been stored on the surface of the baloon that is giving pressure on the water inside. Now I need ...
1answer
66 views

### Why a drop of water acquires the shape of circle while getting absorbed on a bed sheet?

I am quite amazed by this observation as I couldn't prove it or intuitively have a correct reasoning for the circular geometry of the water drop which it acquires while getting absorbed on a bed sheet....
4answers
7k views

### If the pressure inside and outside a balloon balance, then why does air leave when it pops?

Sorry for the primitive question but when we inflate a rubber balloon and tie the end, its volume increases until its inner pressure equals atmospheric pressure. But after that equality is obtained ...
1answer
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### Height of water layer on flat surface

Let's consider some flat surface which extends to infinity in all directions. Suppose we slowly spill some water near some point of the surface. Due to surface tension, the water doesn't spread out ...
1answer
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### Mercury Barometer

Why Mercury surface is flat instead of convex at 760mm Hg level in Mercury Barometer? refer the image attached. note that At top it is a vacuum and surface tension = (pi-po)r/2.
0answers
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### Fast reversible switching from hydrophobic(>120 degrees) to hydrophilic (<60 degrees)?

I found few papers on reversible switching from hydrophobic to hydrophilic Reversible Hydrophobic to Hydrophilic Transition in Graphene via Water Splitting Induced by UV Irradiation Light-induced ...
1answer
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### Diameter to prevent water flow into a closed-end tube?

Imagine I drill three holes of different diameter into a large block of plastic but the holes don't go all the way through. (They form three close-ended tubes, see the image.) I then submerge the ...
0answers
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### Is this wire-melting phenomenon a manifestation of the Plateau–Rayleigh instability; have I done my math right?

In LECTURE 5: Fluid jets from MIT's 1.63J/2.26J Advanced Fluid Dynamics equation 23 is $$\omega^2 =\frac{\sigma}{\rho R_0^3} k R_0 \frac{I_1(k R_0)}{I_0(k R_0)}\left(1 - k^2 R_0^2 \right)$$ and is ...
0answers
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### Meniscus and capillary surface

Can anybody explain what the difference between capillary meniscus and capillary surface?
1answer
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### How to get the height of a constrained, infinite elastic surface?

Suppose I have an infinite elastic sheet, constrained by several poles of height 1. The height of the surface would be 1 at the coordinates of each of the poles, and converge to 0 as the distance from ...
1answer
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### When is the approximation of neglecting the surface energy most useful during estimating the total energy of a spherical system? [closed]

The bulk energy of a spherical system of radius R is proportional to its volume and the surface energy is proportional to its area. The surface energy per unit area, S, and bulk energy per unit volume,...
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### How does different shuffleboard powder affect the disks' speed

I do know there is friction and surface tension involved here but am not sure on how exactly does different kinds of shuffleboard powder affect the disks' speed. So taking into the account the ...
1answer
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### How does surface tension cause glass plates to attract?

I am having trouble with this example : As it says that the contact angle of the glass water interface is $0^{\circ}$ , so the force due to surface tension should act downward on the plates (rather ...
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### Is there any material for which, on increasing surface roughness, changes from hydrophilic to hydrophobic or vice versa?

It is known that on increasing the surface roughness a hydrophilic material becomes more hydrophilic, i.e., it's contact angle decreases on increasing the roughness. Same is true for hydrophobic ...
1answer
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### Contact angle of a thin film problem

I am having a hard time with problem 8 , so can anyone give me some hints. I'll say the things I have in mind I can use the Laplace pressure difference equation to find the the excess inside pressure....
1answer
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### Trying to understand the derivation of the Gibbs adsorption isotherm

I have looked at several deritions online, and the clearest I have found is that on the Wiki page The problem being considered is that of two phases, with an interface of a given area between them. ...
0answers
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### Does angle of contact remain constant for rise of liquid in a tube of insufficient length?

My book states that for rise of liquid in a capillary tube of insufficient length h * R (radius of curvature) = constant. Since the tube is of insufficient height radius of curvature increases to ...
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### Maximum height of capillary rise

I know that when the tube is dipped in a liquid the rise is 2σcos(θ)/(ρgr). So the maximum should be when cos(theta)=1 but the answer is given c
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### Could we explain formation of droplets by symmetry?

I have read at the free online book 'On growth and form' of Thomson D'Arcy that a cylinder has less symmetry than a sphere which is perfectly symmetric and that causes formation of droplets. But ...
1answer
640 views

### Does soap repel water?

Yesterday when I was taking my bath, I scratched my soap bar a bit and threw that bit on the shower floor. There was a little amount of water on the floor where that soap bit fell. To my surprise, I ...
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### Determining the height of water level rise in a combined capillary tube

What will happen when we fix another capillary tube upon a capillary tube which has not enough space to its free capillary elevation?
1answer
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### Why do soap bubbles seem to resist merging?

When playing with soap bubbles in a bathtub, it seems impossible to bring two bubbles together to form a single larger bubble. When two floating bubbles meet, a wall is formed between them. Even when ...
1answer
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### On inserting a thin capillary tube into a large tray of water, does the total surface energy and the total potential energy of the system increase?

In both cases, the system is the liquid in the (tray+tube). I have made reasonably accurate calculations for the gravitational potential energy part. It follows from the calculations that the ...
0answers
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### Theory or method on how to calculate the pressure needed to push a viscous fluid through a narrow slit

I need to calculate the minimum amount of pressure I need to apply to a piece of molten glass to start making it pass through a narrow slit - think 1 kg of glass and a 0.2 mm slit. At this point I ...
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### How can I calculate for surface tension of a plate using formula γ=F/L with known force?

I am doing a lab to find out the change of surface tension of water as the temperature increase. I know the weight of the 2cm*2cm plate and the amount of weight required to break the tension. My ...
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### Why does soap solution forms bubble but tap water does not? [duplicate]

The surface tension of water reduces on addition of soap to it. Then why does normal water not form bubbles but soap does even with less surface tension?
1answer
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### Explaining negative potential energy involved in Surface Energy of fluids

I was studying about Surface Energy in fluids, and here's what I was reading: (a) A liquid stays together because of attraction between molecules. Consider a molecule well inside a liquid. The ...
0answers
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### Is surface tension a Conservative force?

Is surface tension a Conservative force? Can the work done by surface tension be recovered?
1answer
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### Why does water always take an already travelled path? [duplicate]

I asked this question because I want a 'physics' answer. Now let me clarify the question. Assume that we let a drop of water fall on a flat surface. It should theoretically stay still. Now let the ...
2answers
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### Why does water take a “wet” path?

Allow me to explain what I mean... ((I am asking this question in the physics section in hopes of finding a "physics" argument)) I shall make it clear what I mean by demonstrating an experiment... ...
1answer
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### Sound emitted by droplets hitting a liquid surface

when a liquid jet (e.g. water) hits a water surface sound may be produced if, due to Plateau Rayleigh instability, the water jet has formed into droplets. But what exactly causes the sound? Is it the ...
0answers
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### Why does liquid rise to same level in these different capillaries?

I'm having a doubt in the two types of approaches used to calculate the liquid rise in capillaries- one by the excess pressure method and the other by balancing weight of fluid column by the forces ...
2answers
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### Does surface tension increase for a flowing fluid?

When a fluid is moving with velocity V, what becomes of its surface tension, does it increase or decrease in value
0answers
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### Stopping overflow of boiling milk [duplicate]

We all know that milk overflows from the container when boiled. The reason is air trapped under the skin of the milk, can't escape and hence, pushes the skin upwards until it overflows. My mother ...
1answer
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### What are the benefits of surface tension? Why is it so important?

I mean I read that surface tension is the property of a liquid by virtue of which liquid tends to have minimum surface area and behaves as if it was covered with a stretchable membrane. Why does a ...
1answer
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### How fast does liquid rise in a capillary tube?

Take a small diameter tube, stick it in water, and surface tension will drive the fluid up through the tube. How fast is the fluid moving through the tube during this process? Here's my attempt: ...
1answer
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### Curvature of fluid surface next to a floating sphere

I want to estimate the curvature $\kappa$ of the fluid surface next to a floating sphere. The situation is static and shown here: The fluid density is $\rho$, downward gravity is $g$, sphere radius ...
1answer
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### Capillary length and Bond number confusion

The Bond number represents the ratio of gravity forces to surface tension forces, and is defined as $$Bo = \frac{\rho g L^2}{\sigma}$$ where $\rho$ is the fluid density, $g$ is gravitational ...