Questions tagged [water]

Two Hydrogen atoms covalently bonded to one Oxygen atom. One of the more common compounds on the surface of the earth.

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Energy density in pump storage power plant [on hold]

I have $1.5\ \mathrm{km}$ long and $10.0\ \mathrm m$ diameter pipe So it holds $V = \pi\cdot r^2\cdot h=\pi\times5^2\times1500=117\,810\ \mathrm{m^3}$ water. I have calculated that the pump storage ...
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When does water decrease or increase friction?

Water often acts as a lubricant e.g. a wet floor or road, but sometimes the reverse happens e.g. putting on wet clothes. I understand that surface tension is involved e.g. microscope slides sticking ...
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Hot cup condensation

I was wondering if the condensed water dropplets that are left on the table from a PE film coated paper cup filled with water with a bottom headspace come from the air? And if the headspace would be ...
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How hot would it have to be for sweat to evaporate/dissipate before it hits the ground? [on hold]

Essentially this is "how hot a surface would have to be for a drop of water to evaporate before it hits a surface?" Lets say that the drop of water (2ml?) is being dropped from 2 meters. The surface ...
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Why is the kettle loud, but the induction hob is quiet

The question: "Why is a kettle loud?" has been asked and answered many times, including on here: Why is boiling water loud, then quiet? What is the reason for this pattern of noise in electric ...
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Estimation of relative humidity

Assume that we have a box of $1\ \mathrm{m^3}$ with a constant wall temperature of $15\ \mathrm{^\circ C}$. The box was filled with air. The temperature of the air was $30\ \mathrm{^\circ C}$ and the ...
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would connecting a pipe that can carry twice the volume of water to a supply pipe reduce the water pressure in half? If not is there a formula? [duplicate]

I am trying to reduce water pressure by changing pipe size. I want to make a slow peaceful fountain spray.The end of the water line will be pointed straight up so will the weight of the water play ...
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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.
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Air-Water mix flow and pressure

I'm using a system that creates water and air jets. The air line pressure is constant at 1.5 bar while the flow rate changes between 100-2500 cm³. The mixing is done with a water pump that operates ...
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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 ...
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How much steam must a planets atmosphere hold for no condensation to occur at bottom?

If a planets atmosphere contains steam how much would be required in order to have a temperature at the bottom, due to the adiabatic temperature gradient, to prevent condensation and thus rain in the ...
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Darcy applied to surface and groundwater interaction?

My question is, in which of these two scenarios would the ponded water drain more quickly? Darcy's law applied to falling head condition appears to indicate that it would be the a) scenario. I'm ...
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Thickness and refractive index of silica gel layer between fused silica and water interface

I learned that when fused silica contact with water, a layer of silica gel will be formed. However, I cannot find any reference about the thickness and the refractive index of the silica gel. Can ...
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Why can't I see any bubble in my anode during my electrolysis experiment

I am doing an electrolysis experiment using this apparatus The left side is the anode and the right side is the cathode. I am using two 9v battery in series (total 18V DC) to power my apparatus. ...
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Temperature dependency on $D_2O$ stratification

The original problem is the research of low energy consuming process to take away D2O from drinking water. Reading the Q&As on this post, particularly the answer provided by @DjohnM, I would like ...
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In swimming why does gliding help keep the head out of water

In relaxed non-competitive swimming, it is possible to keep the head out of the water while gliding. This can be breaststroke or backstroke (or doing the Tarzan stroke in waterpolo). What is the ...
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Influence of pressure on thermal conductivity of water vapour (steam)

I am looking for an analytical correlation of the thermal conductivity of water vapour (steam) in function of pressure. Apparently the effect is not large, but I would like to confirm this by some ...
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Why isn't the water moving when it is undergoing electrolysis

I understand that in electrolysis of water, the water around cathod is splited in the way of 4H2O + 4e => 2 Hydrogen + 4 OH- . And the hydroxide will move to the anode due to electric field in the ...
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My soap produces less lather as it gets old

I don't know it you have encountered this too but I have observed this "phenomenon" from the last few hundred soaps I have used. As the soaps get older they produce less lather than they produced ...
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Why is more than one ripple created when a rock is thrown onto the still surface of a pond?

I have tried making an analogy with a simple pendulum: if you give it a push it will probably make several oscillations. But why isn't there just one ripple that would carry the energy of the several ...
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Does warmer air of the same humidity condense faster?

Warmer air can hold more moisture but can it also release it's moisture faster when touching a cold surface? If air is warmed (for example by the hot side of a thermoelectric cooler ) before it moves ...
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How does water fill an upside down cup?

On Friday before leaving work, I left one of those smooth carton cups with a lid filled $1/2$ with water on my desk. The desk is made of wood without any special coating. Beside the carton cup, I also ...
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What is the specific heat capacity of ice at −200 degrees Celsius?

All the data I found online just goes as low as $-100\ ^\circ \text{C}$. If the specific heat value of ice at this temperature is unknown, as in has never been tested, would plugging the known values ...
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Features of a Jet of Water

Having created a water rocket that operates with compressed air forcing water out through a bottle's nozzle, I was interested in the some of the features of the jet of water that can be seen using ...
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Ocean Frequencies

I'm a musician studying at uni. For an assessment I'm taking an idea for instrumental tuning which relies on a combination of Pythagorean tuning and Schumann resonances. Whilst Schumann resonance I ...
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Melting ice made with tap water

I recently froze some tap water in plastic bottles and I later made the ice melt completely (the idea was keeping ice bottles nearby me to fight the heat). When the water returned to liquid a lot of ...
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Why water moves in a pipe like a small whirlpool?

I had often noticed when a road is filled with water. And when water moves into a small pipe it moves in a rotating way not straight, it forms a small whirlpool likewise. I don't why does that ...
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Warm or cold air

Which air can be used to dry out food or clothes? Warm or cold air? I've read that keeping food in the fridge makes it dry out. Blowing hot air to the hair also dries the hair out. I'm confused.
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Density of water after absorption

I was wondering if I could assume a water density ~1.0 g/cm3 after it was absorbed by the skin, or other medium. I am particularly thinking on a molecular level, if the nanostructure and size of ...
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Shooting a glass made different with water!

I read about an experiment conducted long back ago. The experiment tells that shock waves are the reason for this. The experiment goes like this, shooting a drinking glass with bullet then bullet ...
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Why doesn't the phase diagram of water look different?

How can sublimation occur at much lower temperatures than 0 degrees celsius provided that the pressure is sufficiently low? The melting point of water is relatively unaffected by the external pressure ...
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Coffee concentrate and water mixed together separated after 2 hours

I'm asking because this makes no sense to me and making sure I'm not stupid. I brewed 10 gallons of cold brew concentrate(TDS 12.2) and mixed it with 10 gallons of water. I moved 10 gallons of the ...
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How is it possible for tall trees to pull water to heights more than 10m?

Which force actually drives water so high up, since pure atmospheric pressure will only get you up to about 10 meters if you're using suction and a long straw and yet tallest trees are over 100 meters ...
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Does water vapour also emit radiation when rising into the air before condensing?

There are topics on how water vapour absorbs radiation ("How does carbon dioxide or water vapour absorb thermal infra red radiation from the sun?"), but what I am looking for is can water vapour also ...
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The Refractive Index of Water after Several Heating and Cooling Cycles

If the refractive index of water under a certain temperature, say 20 degreeC, is 1.33334. Will it return to exact the same value after one or several heating and cooling cycles? Or will it shift a ...
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How long does it take to cool down a drink with ice?

If I have a bottle or container with X fluid ounces of water at temperature Y (say, fridge temperature or room temperature), and I put ice or ice sticks (composed of water) in it that make up Z fluid ...
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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 ...
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QM explanation why hot oil explodes when water pours on it [closed]

I have read this question: Why does hot oil explode when pouring water on it? It explains in a classical way clearly, that the boiling point of oil is hotter then water, and water changes to steam ...
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How small does a hole in a cup have to be to hold water without dripping? [duplicate]

I am creating a drain that lets water in but keeps pieces of plastic out. I need to know the size of a standard water droplet.
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Is Ohm's law valid for water?

I have $E$ (electric field intensity) in water. I want to find $J$ (current density). I don’t know if Ohm's law ($J=\sigma E$) is valid for water. If it is not valid, how do I may find out $J$?
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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....
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Does the mass of a beaker filled with water change due to a mass partially submerged in it?

I believe it should be different as there is upthrust acting on the second block and hence by Newton Third's Law it should act back on the liquid adding to more weight. The answer is given isn't so as ...
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Microwaves and Water Molecules: Radar vs Cooking

I am studying microwave radiometry and confused over this apparent contradiction: Microwaves emitted at 2.45 GHz (~15 cm) are absorbed by water molecules, causing the molecules to rotate under the ...
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Why is it easier to catch mosquitoes with your hand when your hand is wet?

Recently I've noticed that it's significantly easier for me to catch a mosquito with my hand if my hand is very wet (e.g. from having washed my hands and not yet dried them, or from being in the ...
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Sound made by trapped water

When I run water in my bathroom sink and then put the plug in whilst there is still some water left in the basin, there is a high pitch moaning or screeching noise made by my adding the plug. What ...
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Did the Chernobyl power station's water cistern really hold $7000\:\rm m^3$? [closed]

In he HBO TV miniseries Chernobyl, they talk about a cistern holding 7000 cubic meters of water. That is the content of Loch Ness, the deepest lake in the UK. Would the Chernobyl reactor really hold ...
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Relation between rain, time and terrains

I would like to understand whether an approximate relation between the rain and the physical properties of a particular terrain (composed of a specific material such as asphalt or clay or grass or ...
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Why does a cup on water layer create suction?

When I place a cup upside down on a layer of water, say a wet table, and I then try to lift the cup up, I can feel some resistance. So the cup is acting like a suction cup. However the difference is ...
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How is reverse osmosis even possible for desalination?

I don't understand how reverse osmosis for desalination is possible for existing RO membranes of pore size 10 angstroms (A) if the radius of a sodium atom is 3.14 A, chloride is 3.7 A and maximum ...
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How does an ultrasonic humidifier / atomizer affect temperature?

Evaporative cooling is a technique used to cool air by using the evaporation of a liquid. My google research on evaporative cooling shows a ubiquitous concept of forcing air through a pad/membrane/...