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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Why surface tension behaves so differently?

When a needle (or any other object) floats on water, its acting upwards balancing the gravity. But when an object (or may be a needle suspended in water) submerged in water, it acts downwards. ...
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Can a droplet of water bounce back when it hits a water surface?

Is it possible that a droplet of water can bounce from the surface of a volume of water?
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Angle of Contact in Capillary

One Professor recently told me that in an insufficient length capillary, the contact angle doesn't change, its an inherent property which does not change. If the edges of capillary are extremely sharp ...
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32 views

When does a liquid 'wet' a solid surface?

What is exactly meant when it is said that a liquid wets a solid surface. Has it got only to do with the contact angle ?
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A question concerning ad/absorption [duplicate]

Why does a bone dry sponge resist ad(ab)sorbing a liquid whereas a damp sponge readily soaks it up?
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20 views

What is the highest frequency for ripples on water

I want to transmit sound vibrations as ripples on water, as an experimental audio delay effect. Can I make ripples at audio frequencies, that will travel over about 10cm or more? How about other ...
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1answer
37 views

Surface tension in a balloon wtih water [duplicate]

Imagine such situation: We have an empty balloon. We put a long, narrow tube into this balloon and we fill it with water. Then, the volume (and surface) of the balloon will start to increase. The ...
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2answers
35 views

Why the Du Noüy ring method does not depend on the material the ring is made of?

Du Noüy ring method is a way to measure surface tension. Why the measured force, $$F= 2\pi \cdot (r_i + r_a) \cdot \gamma$$ does not depend on the material the ring itself is made of? Wouldn't a ...
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1answer
42 views

What is the difference between pressure in water droplet and that in an air bubble?

The question is at least supposed to be simple but yeah, I need some detailed answers. I have tried thinking about it in the lines of surface tension but it seems what is required of me is more than ...
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43 views

Which side of liquid gas interface is at high pressure?

With respect to what(whether liquid or gas) should I consider that the convex side has higher pressure and concave at lower prsseure? As seen in the example of image it is given that air bubble inside ...
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percolation permeability threshold in Helium before and after lambda point transition

There's an experiment demonstrating the properties of super-fluid Helium compared to normal fluid Helium, in which the Helium is put in a jar who's bottom is porous. The super-fluid can pass through ...
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1answer
36 views

Noncoalescingِ drops on vibrating liquid surface [duplicate]

if you set a dish filled with soapy water onto a loudspeaker or other vibrator and make vibration, When it oscillates, it is possible to hold small droplets on its surface for a long time. I mean, ...
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Does surface tension play a role in planet's shape?

I'm thinking that when the planets and stars were forming along with gravity surface tension also could have played a role in making them spherical. Am I correct?
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Surface tension: the paper clip experiment

In the paper clip experiment, the surface tension of water prevents the clip from falling, thus we can assume it exerts a force of $mg$ (weight of clip) upwards. However, if you try to pull the clip ...
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2answers
41 views

why doesn't water in a inverted tumbler with its mouth covered with a porus cloth fall down ?

Is it due to the greater external atmospheric pressure acting upwards on the molecules or due to surface tension ?
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1answer
29 views

How are probe liquids selected for Surface Energy measurements?

Why are water, ethylene glycol and diiodomethane generally used for surface energy measurement?
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1answer
51 views

Physics behind blowing soap bubbles

Is it possible, using the surface tension of a soap bubble, to calculate the maximum pressure (created by the air flow) it can withstand while still attached to the orifice to prevent it from ...
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2answers
104 views

Why rough surfaces promote nucleation of CO2 in carbonated drinks?

Glassware with scratched/etched surfaces generate more bubbles (video 1, video 2). Why these rough surfaces allow easier heterogeneous nucleation?
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1answer
63 views

Explaining the shape of a raindrop and a drop of mercury

I saw on wikipedia that the shape of a raindrop is explained by using Laplace pressure. But why? Since the drop is in motion, we shouldn't be able to use an hydrostatic law, am I wrong? ...
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2answers
46 views

Why do bubbles group when one pops? [duplicate]

I was recently observing the way bubbles move as they pop and disappear. I noticed that when bubbles destabilize and pop, the remaining bubbles immediately surrounding it will move to fill its place. ...
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1answer
56 views

Torque and Force of Pulley fixed on side

If you had only 1 pulley that is connected to a rotating shaft, and which has a rope circled around it once, with a mass M on one side and with the rope fixed on the other end, how would you then ...
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Beading of water on a hot surface

dropping water on a hot metal surface covered in dust results in the water forming beads. but if the surface is cold the water just flows over it. The temperature of the surface is roughly 120 degrees ...
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2answers
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Does eq. of continuity hold in vacuum too?

When a streamlined flow of water flows down through an ordinary tap, it's cross-sectional area decreases according to eq. of continuity due to atmospheric pressure. If the same apparatus were to be ...
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0answers
37 views

How do impurities affect the surface tension of fluids? [closed]

I want to know what happens to the surface tension of fluids if we add impurities and the reason behind it.
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62 views

Forces causing capillary rise

I have learnt two derivations to calculate the height of the liquid column in a narrow capillary. Here is a derivation using forces and equilibrium : This is the exact derivation given in my book. ...
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Is surface tension characteristic of a fluid?

Does surface tension depend only upon the nature of the fluid or on other factors too like the liquid-solid or liquid-gas interface? I saw in my book definition that $$S = U/A,$$ where $U$ is the ...
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1answer
28 views

Why is the liquid surface concave when it wets a container?

As you can see in this diagram the surface of the liquid is concave, why is the part of the liquid surface adjacent to the container has higher height than the rest of the surface, is it because ...
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22 views

Gibbs isotherm and calculating interfacial tension change from first principles

Question: Is it possible for a solid particle to change the surface tension between two phases? (or: Does a solid particle have a chemical potential?) This question stems from the more ...
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Why is there pressure difference when the liquid surface is curved?

I also want to know why such pressure difference do not occur when the liquid surface is plane even though there are different mediums at both sides of the surface.
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Changing the Density of a liquid while its surface tension is constant

I'm working on Plateau-Rayleigh waves and I want to investigate the effect of density of the liquid on the wavelength of these waves How can I change the density of the liquid while its surface ...
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31 views

Solving for diameter of a glass tube to hold water

I have a tube with length $l$. I then fill it with water. I then turn the tube upside down. What is the diameter as a function of $l$ such that the water does not spill out? I need to do a force or ...
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91 views

Glass tube diameter to hold water when turned upside down

If I have a glass tube that is closed at one end and has length l, how can I find the range of diameters that the tube must be so that the water does not fall out of the tube when the tube is turned ...
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35 views

Why is surface tension positive?

My book describes surface tension as $e=dW/dA$ and work as being negative when it is done against a force. Therefore, if i increase the surface area of a liquid i am doing work on the liquid against ...
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Why do sponges work? [duplicate]

By "sponge" I mean anything used to suck up liquids from surfaces, such as kitchen towels etc. I assume capillary action is a factor, and also maybe surface area and surface energy. What are the ...
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3answers
102 views

What is the direction of surface tension?

How do we define the direction in which surface tension will act? Surface tension is a kind of hypothetical tension in which liquid molecules undergo tension force at the surface. Thus it should be a ...
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Could a hydrophobic surface increase a liquid's resistance to compression/displacement?

Imagine a quantity of an aqueous (yet slightly viscous) solution is resting on a hydrophobic surface with a contact angle around 100°. A downward force is then applied as a (repellant) surface is ...
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241 views

Are raindrops actually “shaped like tears” when they fall?

Raindrops are always pictured like this, people imagine they have this shape when they fall, but is this true? Doesn't this shape create too much drag? What shape do they really have? It would also be ...
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Thermodynamic derivation of condition for equilibrium of triple line

Edit:(4/1/2016) Okay, I get how the required equation arises from force balance. All forces are acting on the same length, so the length cancels out of the equation and what we've got is essentially ...
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Surface Tension and Its Direction?

Can Anyone explain what is the direction of Surface Tension? I studied it is along the Tangential plane to the surface e considered at the location of length element considered.. And within that plane ...
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1answer
104 views

What causes an emulsion to be stable or unstable?

The other day I made a salad dressing based on oil and vinegar. To my understanding, there is a positive energy associated with the surface between the oil and vinegar. The most stable state is also ...
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Does it take energy to destroy the surface of a liquid jet? [closed]

Imagine we have a collision of a liquid jet with an obstacle Does it take time for the surface of the jet to be destroyed while collision?? Or it'll be destroyed immediately?
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84 views

standing waves on a cylindrical jet

as we know, there are some perturbations on a falling jet which are always present and according to their wave number and the radius of the jet, they can grow and decay over time. so, imagine a jet ...
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Plateau–Rayleigh instability according to liquids $Ca$ number

For examining whether viscosity or surface tension dominates each other effects, we can't refer to $Re$ or $We$ numbers because they just tell us about one of them ( surface tension and viscosity ). ...
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1answer
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Surface energy of water [closed]

If $10^3$ small drops of water each of radius $10^{-7}\,\mathrm{m}$ combined to form one single large drop then what should be the energy ? If the surface tension is equal to $0.07\,\mathrm{N/m}$ . I ...
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1answer
42 views

Plateau–Rayleigh instability for liquids with low $Re$ number

I'm working on a project about Plateau–Rayleigh instability for liquids. But I've a question. we can examine the fluids with high $Re$ number that the influence of viscosity is negligible, but what ...
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1answer
86 views

How does surface tension explain the floating needle experiment?

Part 1: After reading some explanation in internet I understood the fact that the molecules of water on the surface have no water molecules in the outward area so it feels a net force towards the ...
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1answer
57 views

What does Low Surface Tension mean?

I have that a book that says "Low surface tension of a liquid helps it to spread over a larger area." . My question is How and Why ? When I say that a liquid A has a lower surface tension than liquid ...
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1answer
77 views

What makes bathroom soap bars to crack during winter season?

Is there some relation between winter season and cracking of bathroom soaps? I noticed that , cracking happens only during winter season.I also learned earlier from physics stack that, During winter ...
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1answer
84 views

How to calculate the speed of a jet of liquid coming out of a nozzle? [closed]

I'm working on a project and i need to calculate speed of a jet falling from a nozzle. But my question is that, is it correct to use $$v=\sqrt{2gh}$$ Or should the speed of the jet be independent ...