What is Water: Definition and 1000 Discussions

Water is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, even though it provides no calories or organic nutrients. Its chemical formula is H2O, meaning that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. Two hydrogen atoms are attached to one oxygen atom at an angle of 104.45°."Water" is the name of the liquid state of H2O at standard conditions for temperature and pressure. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor.
Water covers 71% of the Earth's surface, mostly in seas and oceans. Small portions of water occur as groundwater (1.7%), in the glaciers and the ice caps of Antarctica and Greenland (1.7%), and in the air as vapor, clouds (consisting of ice and liquid water suspended in air), and precipitation (0.001%). Water moves continually through the water cycle of evaporation, transpiration (evapotranspiration), condensation, precipitation, and runoff, usually reaching the sea.
Water plays an important role in the world economy. Approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of the long-distance trade of commodities (such as oil, natural gas, and manufactured products) is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a wide variety of substances both mineral and organic; as such it is widely used in industrial processes, and in cooking and washing. Water, ice and snow are also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, diving, ice skating and skiing.

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  1. starstruck_

    Why does water level stay the same when ice melts inside the water?

    I feel so stupid, intuitively, when we were having this discussion I wanted to say that the level stays the same but when we were discussing with the person beside us, my partner said it would fall because water expands when it freezes, so when it melts, there'll be less displacement, so the...
  2. D

    Does the volume of water affect efficiency of heater?

    Ok, so i did a physics experiment a few days ago and now i have to do a write up. The question is does the volume of water in the calorimeter affect the efficiency of the immersion heater? Could someone pls explain to me what happens & y? My results showed that as you increase the volume, the...
  3. K

    Diffraction work differently on water waves vs light waves?

    When the water waves go through one wide slit (slit wider than wave length), there's no fringes, the water waves spread all over the sides, like in this pic: http://electron6.phys.utk.edu/light/images1-3/misc3b.jpg or in this pic...
  4. R

    Why Does a Water Stream's Pattern Change When Interrupted?

    I observed something which I've never seen before. We left the tap open and the water stream was flowing in a particular pattern. When we placed a beaker under the water stream, the pattern disappeared. And the pattern itself was oscillating. Here's the video link. Below the the photos of the...
  5. I

    Water Mass in Leaking Container

    Homework Statement Water is poured into a container that has a leak. The mass m of the water is given as a function of time t by m = 6.00t 0.8 - 2.75t + 22.00, with t 0, m in grams, and t in seconds. (a) At what time is the water mass greatest? (s) (b) What is that greatest mass? (g) (c) In...
  6. G

    US-Style Water Heater: Tips for Optimal Performance and Safety in the UK

    Hi all, I've just moved to a house in the Highlands whose previous owner was American, and insisted on installing US appliances, presumably shipped over at great expense. I wonder if our US friends on here could help with the water heater: Is it just California state law to write all that...
  7. H

    Water heater - storage or tankless

    Hi all, I'm thinking of buying a new water heater, and still confused to choose between storage water heater vs demand water heater (tankless). Can anybody give me the pros and cons of each? what I have so far: 1. Tankless consumes more power, and the longer you shower, the more it consumes...
  8. K

    Finding Depth of Water Loss Using Surface Area

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  9. B

    How Water Dept's of major metros maintain water pressure?

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  10. M

    Drag in water - object in a tunnel/tube

    Hi everyone I was reading about drag, and didn't quite find what I was looking for. A general drag equation is : 0,5 x ρ x u² x Cd x A, where there are some drag coefficients that have been found during laboratory experiments. Let's say a sphere with a radius of 1m is traveling at 2m/s under...
  11. D

    Water level rise in a tank, continuous flow in, high exit

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  12. R

    Can probiotic be made just from sugar and water solution

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  13. L

    How much water is converted to ice?

    Homework Statement A 0.530 kg sample of liquid water and a sample of ice are placed in a thermally insulated container. The container also contains a device that transfers energy as heat from the liquid water to the ice at a constant rate P, until thermal equilibrium is reached. The...
  14. HelloCthulhu

    What is the molality of 1M NH4OH in 70.092ml of water?

    Homework Statement What is the molality of 1M NH4OH dissolved in 70.092ml of water? What is the total mass of the solution? What is the total volume? What is the concentration percent? What is the molar concentration? 1M NH4OH = 35.046g density of water = 1g/ml density of NH4OH = 0.88 g/ml...
  15. S

    Can someone help me find a method to measure water level in a tank

    At the outset I am a novice in physics. i have constructed a rain water storing tank with a capicity of 1,20,000 litres. I propose to seal the tank so that there is no light penetrating inside the tank. My question now is how do I measure how many feet of water is left inside the tank? Can...
  16. A

    Time for Hot Water to Cool -- Calculation....

    The title says it all. I would like to know how to calculate the time for boiling water to cool off. Assuming the temperature of the room is not changing and there is a constant degree of air flow over the water. Really I would just like to know how to go about calculating this. Thanks in...
  17. C

    How Can I Mix Different Colours of Paint Without Them Blending Together?

    I am looking for a way that I can mix many colours of paint into the same container without it blending together and making other colours. I make liquid art and have seen others make images where i can see many colours in the liquid. The base of what I use at the moment is methycelluslose ...
  18. PainterGuy

    The shell strikes the water at the same speed?

    Hi Please have a look on the attachment. Do you also agree that the shell strikes the water at the same speed? It seems false to me. The vertical and horizontal motion is independent of each other. When the shell is fired horizontally, it starts descending toward the ground from less height...
  19. R

    Calculating Water Volume in a Tank Using Pressure Measurements

    Homework Statement on a flat desk is an aquarium with a volume of 640 cm3 ,t's not full of water. The pressure to the bottom of the aquarium is 3 times bigger than to one side of it, how much water is in the tank? Homework Equations is the pressure, is the normal force, is the area of...
  20. B

    Water Bottle Design Using Polynomials

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  21. A

    Calculating/3D Modeling Salt Water Current Paths

    Just to clarify, this is not a homework or coursework question. I was wondering, if you have a large container of salt water and place two electrodes on either side, the current will pass from one electrode to the other through the salt water medium. Is the a way to calulate or 3D model the...
  22. R

    Question about gravity, water and snow

    Suppose I fell from a mountain, which would hurt less: A) Falling on a very huge pile of powder snow or B) Falling on water It's a serious questions! Thanks!
  23. S

    How to dissolve/ dispress Fe3O4 nanoparticles in water ?

    how to dissolve / good dispersion Fe3O4 nanoparticles in water and that solvent have with / without toxic to fishes?
  24. G

    Can we accurately measure water pressure using DIY water towers?

    I'd like to explore water pressure by having students build water towers out of both 2-liter bottles and thinner 1 liter bottles. 1. Assuming they build towers of the same height and fill them with the same type of water, we should see the same water pressure for identical heights within the...
  25. R

    Resistance of a water heaters heating element?

    Homework Statement Household water heaters use a 240 V rather than a 120 V source. What is the resistance of a water heater's heating element if it heats 40 gallons (151 kg) of water from 15 C to 60 C in 15 min Homework Equations P = IV P = I^2R I = dq/dt The Attempt at a Solution Honestly no...
  26. M

    Why doeslight "turn" when it travels through water?

    This might be a silly question. Ever since I can remember, I've been taught that when light crosses the boundary between two mediums with different refractive indices, its trajectory changes due to a reduction or increase in its speed. I've never given this a second thought, but today I...
  27. caters

    Chemical water treatment: Acid base reaction

    I was thinking of a hypothetical waste system that uses nanotechnology to its advantage. At the individual level, waste just passes through into pipes when flushed like it normally does. But once it reaches the water treatment plant there is an initial filter to catch solid waste(in other...
  28. D

    Relative velocity and water skier

    Homework Statement Homework EquationsThe Attempt at a Solution The water skier makes an angle of 20 deg with the axis of the boat. I do not understand how to get the other angles.
  29. C

    Compressing a bottle with water - initial velocity of water

    Imagine that we have a closed plastic bottle filled with water and then we punch a hole with area A in its cap. How can I find the initial velocity the water will he "fired" with if we squeeze the bottle applying stress S? Assume that we know all about the bottle (moduli, change in volume etc...
  30. Solomei

    Plant's response to lack of water

    Ive observed my own plants for quite some time now, and of course done my studies on nutrition. What I've recently learned (observed) is that when a plant lacks water, the flowers seem to be the last ones standing, while possible death from other factors preserves older or newer leaves...
  31. G

    Water pressure vs pressure drop

    Hi guys, I know the difference between these two things but I'm struggling with something that I hope someone could help me with. What dictates the water pressure needed for a "system" to work? I would imagine that if you've calculated your system to have a pressure drop of 1 bar (for...
  32. J

    Directional Grooves on the Interior of Pipes

    Hey everyone! My name is Jing and I am participating in a one month summer program called SHAD where 800 high school students across Canada come together to try and solve some of the world's most multi-dimensional problems. One of the aspects of this program is the Entrepreneurial Project, where...
  33. S

    Van der Waals vs. Hydrogen bonds

    I know that the two are different thing, that vdW appears in inert gas crystals and alike while hydrogen bond bonds molecules of water. My question is, how does the potential look for hydrogen bond? For vdWaals we have the two terms proportional to 1/R^6 that describes attraction and 1/R^12...
  34. Anachronist

    Water flow from pressurized tank - versus temperature

    Bernoulli's equation gives us this as the flow rate from a pressurized tank: $$v = C_v \sqrt{2gh + \frac{p}{\rho}}$$ where ##C_v## is the velocity coefficient, ##g## is the acceleration due to gravity, ##h## is the height of the water above the exit hole, ##p## is the excess pressure above...
  35. Gotbread

    Using a centrifuge to extract heavy water (help with the calculations please)

    Hello everyone! I have seen several DIY projects which successfully gathered heavy water from normal water. For example Cody from codys lab used electrolysis to "enrich" the water. This however is a messy process. So i became curious, if this can be done easier by centrifugation. Based on...
  36. J

    Optics: What is the color of the object as seen from under water?

    Homework Statement Homework EquationsThe Attempt at a Solution [/B] Since wavelength of light reduces on entering water , then the wavelength of light entering the eyes of diver is less than the wavelength of green light . Out of the given options , option B) i.e blue color is the only one...
  37. J

    Optics : White light incident on water drop

    1. Homework Statement Homework EquationsThe Attempt at a Solution [/B] I know that if white light is incident on a triangular prism , then lights of different wavelengths are deviated by different amounts and dispersion occurs . But I am not sure what would happen in this case where we have a...
  38. T

    Amount of energy required to heat a kg of water?

    So recently I've become familiar with concepts like specific heat, and we use a formula Q=mcΔT to calculate the Joules necessary to heat up say a kg of water from 50 to 70 degrees celsius. Now I was wondering if there is a equation that incorporates the amount of heat lost to the atmosphere...
  39. Zaya Bell

    Heat Transfer in Water: Convection, Expansion & Conduction

    Looking back to heat transfer by convection, which means denser molecules move down, lighter molecules move up. And then water at 4°C expands when cooled further, and at 0°C it contracts when heated. So if water at 0°C in a container is heated from the bottom, its molecules should...
  40. N

    How sodium alginate changes the viscosity in water?

    Hello everyone. I have a question about the sodium alginate (NaC6H7O6)n. Recently, sodium alginate is widely used for fabricating edible bottle. And I also try to utilize sodium alginate for controlling the viscosity of water. I found that with small amount of sodium alginate powder in DI water...
  41. Vital

    What happened to the boiling water

    Hello! This question is not about a particular homework exercise, or any exercise, but rather an astonishing real life fact, which I just experienced, and, as I am still on my way to becoming educated in science, I would like to ask for your help on how to explain this phenomena. I had a...
  42. B

    Are sounds louder under water?

    Given equal power at the sound source - is the amplitude (in pascals) of sound pressure waves greater in water than in air? - What is the mathematical or physical bases of any difference?
  43. Monsterboy

    Solve Water & Salt Problem in 5 Hrs

    Homework Statement A tank contains 800 gal of water in which 200 lb of salt is dissolved. Two gallons of fresh water runs in per minute, and 2 gal of the mixture in the tank, kept uniform by stirring, runs out per minute. How much salt is left in the tank after 5 hours ? Homework Equations...
  44. ActuatorA

    Water speed and bullet penetration

    This may be an odd question but I am wondering if water speed affects a bullet's ability to penetrate water. Pardon my lack of knowledge, but I am aware that low caliber bullets can penetrate water past 3ft (Thank you Mythbusters). However, the tests they completed were all based around a pool...
  45. J

    Mixing Ice and Water: Final Temp & Composition

    Homework Statement 300gm of water at 25°C is added to 100gm of ice at 0°C ,find the final temperature of the mixture .Also find the final composition of mixture . Homework Equations [/B] Specific heat of water = 1 cal/gm/°C Latent heat of fusion of ice = 80 cal/gm The Attempt at a Solution...
  46. J

    How Much Steam Is Needed to Heat Water from 24°C to 90°C?

    Homework Statement The temperature of 100 gm of water is to be raised from 24°C to 90°C by adding steam to it .Calculate the mass of the steam required for this purpose . Homework Equations Latent heat of vaporisation of steam = 540 Cal/g The Attempt at a Solution [/B] Let 'm' be the mass...
  47. J

    Calculating Equilibrium Temperature of Ice and Water Mixture

    Homework Statement 1Kg ice at -10° C is mixed with 1 Kg water at 100°C .Then find equilibrium temperature. Homework Equations Specific heat of water = 1Cal/g/°C Specific heat of ice = 0.5 Cal/g/°C Latent heat of fusion of ice = 80 Cal/g The Attempt at a Solution [/B] Heat required by ice...
  48. A

    Calculating Water Force and Moment in a Fresh Water Storage Tank

    1. Homework Statement A fresh water storage tank in a factory is shown in the figure above. Its top side is denoted as C, the narrow side as B and the long side as A. In order to allow regular maintenance and cleaning side A is hinged at its bottom edge and secured using a heavy-duty clasp at...
  49. J

    Finding Check Valves for Water Droplets

    I'm having trouble finding any valves to use for my certain application. What I'm doing is trying to capture water droplets into a sealed container. What I need is some sort of check valve that needs nearly no pressure to let water through, but keep it contained once it has gone through the...
  50. jedishrfu

    News Recent NOVA on Flint and Its Poisoned Water

    This NOVA documentary outlines the events of the Flint water crisis along with the science that uncovered the truth: http://www.pbs.org/wgbh/nova/body/poisoned-water.html It also gets into how the science, the citizens of Flint and the scientists were repeatedly attacked and discounted by the...
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