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When you are sucking a liquid with a straw, you are pulling a liquid by creating a low pressure in your mouth. This is similar with capillary rise: the surface tension has for effect to reduce the pressure of the water beneath the air-water interface. As a result, water rises until the pressure is balanced. The "pull" is transmitted down by the cohesion ...

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There are three questions here: Why didn't the water spread in the paper ? What defines its shape ? Why does it shake ? Answer 1: when the drop approaches the surface, air trapped between them needs to escape. In some conditions (speed and size of drop, roughness of the paper), this is slow and consumes enough energy to use up all the momentum of the ...

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It is by no means certain that when you open the tap the flow is automatically turbulent (although going by your top picture it appears to be). Open the tap just a little to allow a continuous stream of water to exit and you'll see the flow is not turbulent but so-called laminar. Whether flow through a pipe (and by extension when it leaves that pipe) is ...

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Surface tension does exist "in space", which I take you to mean "without gravity". Surface tension in liquids is simply the attractive interactions between the molecules of a liquid. That exists whether there is gravity or not. I think most pens will not work well without being in the proper orientation in gravity, though. If you try using a normal ballpoint ...

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You are right - the contact angle is indeed a function of the forces between the liquid and the wall. So when the capillary rise equation predicts the rise for a liquid with a given contact angle, it accounts for this effect. So how does the contact angle relate to this energy? The Young-Dupré equation tells us that the relationship is: ...

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Your conjecture is correct: The rise of a liquid in a capillary is not just a function of the liquid-air surface tension but also the liquid-solid surface energy, AND this liquid-solid surface energy is present in the equation and its effect is represented by the contact angle parameter in the capillary rise equation. Derivation of the capillary rise ...

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It has to do with water tension. When the glass is filled to the very top, the water causes a dome to form. The cork floats to the very top and this top is in the middle of the glass. When the glass is half full, the water closer to the edge of the glass is at a higher level than in the middle. This causes the cork to float to the side.

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This is because that the cork floats to the highest point it can. The water is not flat in the glass - it curves up a the edges so the cork gets higher by going to the edge. When the glass is full, really completely full just above the level of the rim of the glass, the water will be bowed a bit so that it goes down at the edges and is highest in the ...

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Just to extend my comment about Capillary action which is the reason for the liquid rising through the capillary (straw in your case), I show this animation of how the diameter of the capillary (d) effects the height of the liquid (h) that rises above the contact surface. The relation of $h$ and $d$ used to simulate this is taken from wiki page which is  ...

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You have 3 different materials in your experiment: a liquid (coffee, could be water), a solid (plastic straw) and a gas (air). You have interfaces between all three: liquid-air, liquid-solid and solid-air. In the case of the plastic of your straw, adhesion forces are stronger between plastic and water than plastic and air: so a force will tend to make the ...

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The liquid rises due to surface tension. In this case the adhesion between liquid and cup material Is higher than cohesion between liquid molecules. So it is higher than liquid in cup. I think the liquid in the straw that remains after removing will be lesser than the liquid that you saw rising while in the cup. Try for transparent liquids. The liquid in the ...

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