# Questions tagged [capillary-action]

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### Effect of acceleration on rise of liquid in capillary

What would be the effect of vertical acceleration on the rise of liquid level in a capillary tube. Will the liquid not rise if we provide the system a downward acceleration equal to $g$ ? Consider ...
444 views

### Conservation of Energy in Capillary Tube

The capillary action lets a liquid rise in a narrow tube to a certain height. In this, the liquid gains some potential energy. According to the Conservation of Energy, the energy must come from ...
1k views

### Why would water rise if the height of the capillary tube above the water surface is decreased?

While studying fluid mechanics I came across a section which say: If a tube is submerged in water and some part is empty Water rises in a capillary tube say to height $h$ .Now changing the length ...
94 views

### Can a capillary opening lift a huge load?

The problem I pose is about an application of the Pascal law and capillary action. It is based on a plot which I describe hereafter. Imagine a one side sealed cylinder with a piston on the other side....
100 views

### Diameter Shifting Capillary Tubes

Is there any known material of which to construct a capillary tube that would make it possible to compress the diameter of the capillary tube while maintaining the internal shape? Intent being that ...
831 views

### Why is the angle of contact different for a meniscus and a droplet in the same water/glass/air environment?

There's gravity, there's adhesive and cohesive attractive forces. Fair enough, most materials seem to compare water to mercury in capillary tubes when explaining capillary action and above properties ...
795 views

### Contact Angle 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 ...
990 views

### Bent capillary tube

What would happen if I bend a capillary tube and use it as shown in figure? 1.Will the water(or any other adhesive liquid) level remain same as before bending? 2.or it will come up till end? 3.Or ...
3k views

### How does capillary action work in tubes which are closed at the top?

In all textbooks the examples and descriptions use tubes which are open at both ends. Our teacher remarked that if it were closed at one end like a test tube (albeit a thin one) even then capillary ...
36 views

### 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 ...
1k 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. ...
2k views

### How to move a bubble which is trapped by the capillary pressure?

I have a question about how to move a trapped bubble in a tube. If we assume to have a horizontal tube, with water on each side of the bubble. The point to the left of the bubble is point 1, while ...
299 views

### Direction of surface tension

consider the capillary tube shown in the diagram. According to my book the direction of surface at the point of contact is towards the surface as in diagram 2, but shouldn't it be away from as in ...
51 views

### Capillary bridge force function given volume and distance

Given two surfaces and a fluidic glue with sufficient adhesion, what is the force provided by the capillary bridge provided the cohesive properties of the glue, volume, and distance between the ...
453 views

### Why don't we include the adhesive and cohesive force while calculating rise in a capillary tube?

The contact angle of a liquid solid interface is explained by saying that the liquid surface must be perpendicular to the resultant of adhesive cohesive and gravitational forces acting on it, since it ...
254 views

### Capillary turned upside down

I have a glass capillary filled with water at half volume. The meniscus shape is well known. I turn the capillary upside down. The water does not flow out. What shape the new meniscus will be? Roughly....
512 views

### Surface tension & capillary action

While deriving the equation of height to which the fluid rises, we say that the surface tension pulls the water till the weight of water balances it, my doubt is that how can any force pull on ...
2k views

### Surface tension and capillary rise

The expression for the height rise in a capillary tube is well known, and the surface tension of the liquid air interface is involved. But as I understand the adhesion force between the water and ...
965 views

### Can capilliary action move liquid against gravity?

I was wondering if it was at all possible to very slowly suck up water from a cup with a rope, and then deposit the water into another cup on a 3cm thick book or similar object. Here is an example ...
13k views

### Why does a paper towel absorb water upwards?

When I touch a paper towel to a drop of water I can see the water move upwards into the paper towel. What force is responsible for this gravity defying phenomenon?
471 views

### Is surface tension the result of a pressure drop over the air-water interface or visa versa, for a two sphere system?

For a liquid bridge between two spheres the Young-Laplace equation states that: $\vartriangle p= \gamma\bigl(\frac{1}{R_1}+\frac{1}{R_2}\bigr)$ where $\vartriangle p$ is the capillary pressure ...
828 views

### Capillary effect to pump water up to cool water

Chinese scientists demonstrated anti-gravity pump, which uses capillary effect and super-hydrophobic screen to flow water upward by 1cm using internal energy of water. How much water will be cooled ...
2k views

### How does this capillary-action setup not become a perpetual motion machine?

If you have a very thin glass tube and you place it into water, let's say the water in the tube rises to the height of $x$ mm from the surface of the water. What would happen if you poked a hole in ...
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### Size of a glass capillary for noticable capillary action

How big would a glass capillary have to be to have noticable capillary action? Also, does capillary action happen in plastic tubes?
3k views

### Capillary action and perpetual motion

From Wikipedia Capillary Action Thus for a 4 m diameter glass tube in lab conditions given above (radius 2 m), the water would rise an unnoticeable 0.007 mm. However, for a 4 cm diameter tube (radius ...
4k views

### Why doesn't this capillary action generator work?

So I was doing a bit of reading. Apparently the obstacle to generating energy from the forces driving capillary action is breaking the surface tension at the top of a capillary tube. It is just ...
85 views

### liquid trapped in wet sponge

If you soak a sponge in water, or some other liquid, and then let it hang then some liquid will flow down due to gravity but not all, some amount will remain trapped in the sponge by the capillary ...
417 views

### Does gravity affect water permeability?

Suppose I have an approximately rectangular prism composed entirely of folded paper. If I place 600lbs on top of these rectangular sheets of paper, the paper should compress. How does this affect ...
198 views

### Violation of conservation of energy… or not? [closed]

The work done by surface tension is double the increase in potential energy. This is a clear violation of conservation of energy. What is the flaw here? Work done by surface tension is \begin{align} ...
636 views

### “Troll physics”: What is wrong with this perpetual machine? [closed]

I think this will not work because the water can't flow out of the tube. (But what if we make the other end a little wider, will the water stop right before that part? What confuses me is that even a ...
38 views

### where does the energy for capillary action come from? [duplicate]

I think capillary action occurs because water molecules have a little magnetic field with poles so they can stack up on each other somewhat. When it happens though, where is the energy derived from to ...
255 views

### Capillary action column height in a tube fitted inside another tube?

I was thinking about how would capillary action change in a tube (classic example) and in a tube fitted inside another tube (considering water as the liquid involved). Height of liquid column: where:...
1k views

### Capillary action meniscus height in a tube fitted inside another tube?

I was thinking about how would capillary action change in a tube (classic example) and in a tube fitted inside another tube (considering water as the liquid involved). Height of liquid column: where:...
610 views

### Will a drop of liquid flow from from the wide opening to the narrow opening of a thin funnel by the effect of air pressure?

We have a funnel that is thin enough to keep a drop of liquid inside it as shown in this figure. Assuming that the funnel is placed on a horizontal table, will the drop flow from the left side to the ...
3k views

### How is sweating a pipe an example of capillary action?

I learned how to sweat a pipe today from my father. If you're not familiar with the process, this might help. One thing that jumps out at me is this line (from the above link, as well as my father's ...
1k views

### Capillary in a slanted tube with a bend

So I've read a question on here about Capillary action in a slanted tube, but my question goes a little further. Firstly though, could someone explain to me what is meant by the only answer to that ...
2k views

### Can capillary forces be used to make hydro electricity?

Could a device with very thin columns of glass or something that attracts water more be used to pull water up and then release it to drive generator and perhaps add vacuum. I have been wondering ...
1k views

### Ink in a pen on an artificial satellite

In an artificial satellite, a space traveler tries to fill a pen by dipping it in ink. The amount of ink filled in the pen as compared to the amount of ink filled on the Earth's surface will be: ...
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### How is the water meniscus at the edge of a capillary tube?

Suppose we have a capillary tube in which water can rise to a height of x cm. If we dip the tube such that the height above the surface is less than x, then how will the water meniscus be at the edge ...
18k views

### Capillary tube of insufficient length

I was wondering if we have a very thin glass tube placed in a tub of liquid and the portion of the tube outside the liquid is lesser than the height to which the liquid can rise because of capillarity,...
703 views

### Sandstone getting soaked with water [duplicate]

I have seen someone putting a sandstone in water. With only about 10% of the stone sitting in the water. One could see the stone getting soaked with water. So there must be a force, which lets the ...
44k views

### Problem understanding the capillary action equation

As you know the equation of capillary action id given by: $h=\dfrac{2\gamma\cos\theta}{\rho gr}$ Where: $h$ is the height the liquid is lifted, $\gamma$ is the liquid-air surface ...
404 views

### Why do new towels dry better after a few uses?

Most of you will be familiar with the phenomenon: you have bought a new towel and you first have to wash it or use it a couple of times before it starts to work properly, i.e. dry your body after ...
14k views

### How does a sponge “suck” up water against gravity?

If I take a sponge and place it in a shallow dish of water (i.e. water level is lower than height of sponge), it absorbs water until the sponge is wet, including a portion of the sponge above the ...
919 views

### Absorption of Water

I was just watching the videos Chris Hadfield put on youtube from space, and was wondering why water doesn't get absorbed as well onto his toothbrush in space? And what characteristic of toothbrushes ...
155 views

### Equidistant coffee rings in a mug: pinning boundaries coupled with migration of solute or just sip volume?

I understand that you get coffee rings on a table as a result of solute migration (solutocapillarity) towards the pinning of the circumference of the coffee ring [Deegan et al.]. Below is an ...
9k views

### 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 ...
2k views

### 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 left....
The velocity of fluid of viscosity $\eta$ through a capillary of radius $r$ and length $l$ at a distance $x$ from the center of the capillary is given by; $v=\frac{P}{4l \eta }(r^2-x^2)$ (where $P$ is ...