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. F

    Stagnation point and a water dam

    Hello Forum, I am clear on what the pressure at a point ##P## is on the wall of heigh of a dam at a certain depth ##d## below the water free surface: ## \rho g d+P_atm##. The deeper we go the higher the pressure. Now let's consider a different scenario: there is initially no water and water...
  2. J

    Thermodynamics: Dropping a hot horseshoe into a pot of water

    Homework Statement A freshly-forged iron horseshoe, with a mass of 0.549 kg is dropped into a 0.281 kg iron pot which contains 1.60 kg of water at 21.4 oC. After the horseshoe, pot and water reach thermal equilibrium they have a temperature of 29.8 oC. Assuming the pot and the water were in...
  3. A

    Surface Tension of needle on water

    I attempted the question but it was wrong... I don't understand where i went wrong my working seems logical, can someone please help. When a needle is gently placed on the surface of still water (γ = 0.0730 N.m-1) it can be supported by surface tension if the mass of the needle is small enough...
  4. C

    Pumping water upwards in a column

    Homework Statement Suppose you have a tank 10 m high. The tank is currently filled 5 m high with 1000 kg of water. How much energy does it take to pump in another 1000 kg of water from the bottom to fill the column to 10 m? (Ignore friction, etc.) Homework Equations E = m*g*h The Attempt at...
  5. T

    Would this work? (air filled tube inside a water filled container)

    Hey, I am from Turkiye, 17 yo and studying at high school. I have a project and would be better to know whether or not my project will work. I tried to draw it simply on paint and will tell you about some important points of it. Image 1 is the main body, its something solid and waterproof. It...
  6. T

    Head Calculation of a hot water circulating pump

    Hello, I have the following hot water system. I have a water heater with a pressurized cold water inlet. A re circulation line is taken near the farthest fixture passed through a circulating pump and back to the heater inlet. When calculating pump head, do I calculate pressure drop in the entire...
  7. J

    Freezing of water inside a hollow sphere which is rolling

    Homework Statement If we have a hollow ball completely filled with water which is rolling without slipping on a horizontal ground. If the water freezes which of the parameter will remain unchanged- angular speed, angular momentum, linear momentum, kinetic energy, total energy Homework...
  8. T

    I Explaining the size of a water molecule

    I am a longtime producer and host of a children's radio show on our local public radio station. It's springtime and the rivers are running and I'm working up a little bit of shtick about water for the show. Water molecules are among the smallest, and one goal of the piece is to relate the size...
  9. wildonion

    Kinematic viscosity for water on Mars

    Hi - I am trying to understand the relationship between atmosphere pressure, viscosity, and density - specifically water. Is there are way to estimate a range of dynamic viscosity and density values based on varying atmospheric pressures and/or temperature that I could use on any planet. Thanks...
  10. J

    Ball floating on the surface of water

    Homework Statement Homework EquationsThe Attempt at a Solution When air is evacuated , atmospheric pressure pushing down the cork is eliminated , cork should rise a little i.e option b) . This is incorrect . What am I missing ?
  11. J

    Drinking water through a straw

    Homework Statement Homework EquationsThe Attempt at a Solution My understanding is that while sucking , the pressure inside the straw decreases .Atmospheric pressure on the water surface pushes the water down such that it rises in the straw, into the mouth . I don't understand how there...
  12. Isaac0427

    How is water produced in photosynthesis?

    I have looked everywhere, but most of the sources say water is not produced (which is not true), and some sources, such as my biology textbook, simply say it is produced. I know for every 6CO2 put into the Calvin cycle, 6 oxygen atoms are put into 2*G3P. Where do the other 6 leave the Calvin...
  13. Stephenk53

    Water resistance in a flashlight

    I recently made a flashlight/ laser pointer that can charge my phone, and I was wondering as to how I could make it resistant to the rain while allowing the top to be removable to switch out the batteries and make repairs. I also plan on making it attach to my arm like a gauntlet. So how could I...
  14. M

    Inteference Fringes of Double Slit Experiment in Water

    Homework Statement Suppose a double-slit experiment is immersed in water (with an index of refraction of 1.33). When in the water, what happens to the interference fringes? Homework Equations λ = λ0 / n y = (λmL) / d d = distance between slits L = distance to viewing screen n = index of...
  15. WhiteWolf98

    Determining the coefficient of viscosity of water (Graph Problem)

    Homework Statement So, the question is based around an experiment to determine the coefficient of viscosity for water (by capillary flow). Part of the experiment involved producing a graph of Q against h. This graph is supposed to be linear, and is supposed to pass through the origin. As can be...
  16. P

    Calculating Heat Transfer in a Water Bath with a Changing Volume and Temperature

    Homework Statement A cylinder is fitted with a piston and is in thermal contact with a heat bath at 273K. Initially the volume in the cylinder is filled with 10kg of pure H2O and about half of this is liquid and the other half is solid. The piston is lowered so as to reduce the volume by 2 ×...
  17. P

    Calculating Speed and Force in Water Jet Impact | Fluid Mechanics Homework

    Homework Statement "A jet of water issues from a nozzle, of diameter h_1=0,102 m (and depth b=1 m), at a speed U_1=2,02 m/s. The jet strikes a flat plate of mass M=2,05 kg, as shown in figure, and it breaks into two jets of equal speed and diameter h_2=0,122 m and h_3=0,102 m. Determine the...
  18. G

    Plastic particles found in bottled water

    So recently news broke about there being plastic particles/contaminants inside major brand water bottles (plastic), so since I don't drink bottles water but use some plastic bottles myself to fill in some fresh water from the local forest I then wonder how did the plastic particles got in the...
  19. zul8tr

    Hydrostatic force on identical containers filled with equal volumes of water

    In the sketch are 2 identical containers filled with equal volumes of water. Which has a greater absolute vertical force only on the conical wall and by what relative amount? Not a classroom or homework problem.
  20. EF17xx

    Tuning fork standing wave in a water pipe

    Homework Statement The question is as follows: The distance between the two positions of maximum loudness is x What is the wavelength of the sound emitted by the tuning fork ? A. x/2 B. x C. 3x/2 D. 2x the correct answer is answer D. Homework Equations Pipe with two ends open λn=...
  21. P

    Where can I find water vapor images?

    I am searching for images of the daytime sky taken within the water vapor absorption bands at 940nm, 1600 nm, 1860 nm, 2700 nm or 2900 nm. Specifically I am trying to see if multispectral images of in-band and adjacent out-of-band photos could be subtracted to show areas of slight water vapor...
  22. EF17xx

    Unpolarised light incident on a water surface

    Homework Statement Homework Equations n1/n2 = (sinθ2)/(sinθ1) = v2/v1 The Attempt at a Solution Moving from a lower refractive index to a higher refractive index. ( Lower density to higher density means faster speed to slower speed) The answer is answer B, I don't understand why.
  23. J

    Random Walk of KMnO4 in Water: Why Do We Observe Non-Probabilistic Behavior?

    I had a question regarding the random walk problem in statistical mechanics. If I drop, say, one molecule of KMnO4 in a beaker of water, what we generally observe (spread of KMnO4 to the ends of the beaker) is different from what we should get from probabilistic assumptions. I must be going...
  24. P

    How would you solve the water abundance XPrize?

    Hi everyone, This was the criteria for the competition: The Water Abundance Prize tasks competing teams with developing technologies that can harvest 2,000 liters (528 gal) of water from the atmosphere each day, using only renewable energy at a cost of no more than two centers per liter (0.26...
  25. G

    Air pressure holds coaster on glass: What if only half full?

    Hi. If I fill a glass with water up to the top and close it with a coaster, I can turn it upside down without the coaster falling off and spilling everything. Usually, this is explained with the atmospheric air pressure being bigger than the pressure of the water inside the glass (hence, it...
  26. K

    Finding power as a function of time in transferring water

    Homework Statement A completely filled cylindrical tank of height H contains water of mass M. At a height h above the top of the tank there is another wide container. The entire water from the tank is to be transferred into the container in time T such that level of water in tank decreases at a...
  27. MermaidWonders

    MHB Analysing Salt Buildup in Water Reservoirs

    Alright... Here's one I encountered today. Suppose the water reservoir holds 100 million gallons of water and supplies a city with 1 million gallons a day. The reservoir is partly refilled by a spring which provides 0.9 million gallons a day and the rest of the water, 0.1 million gallons a...
  28. A

    Alka seltzer in water question

    Hi everyone. I was testing the pH of water that had alka seltzer placed in it. I used Bromothymol blue indicator to see the pH. The color changed to yellow, which suggests that the water was now acidic. I assume this is because of the CO2 bubbles that form which can acidify the H2O. Am I...
  29. R

    Calculating water pressure and the required mass of water

    Basically what I'm trying to do is calculate the amount of water it would take to generate a given pressure at the water tap. Or to put it more simply I'm trying to figure out where the water line is damaged, well more for fun then actually being practical. The water system is simply a well on...
  30. kyphysics

    Study: Major Bottled Water Brands Contaminated w/ Plastic

    https://www.yahoo.com/lifestyle/top-bottled-water-brands-contaminated-plastic-particles-report-013209098.html What conclusions should we draw? I drink exclusively bottled water too. Can't remember last time I had it unbottled.
  31. ConnorJohn

    Question about lifting water through a water pipe.

    Hello! First post, hope you all can help me out. I’m a peace corps volunteer in Nepal and am trying to implement drip irrigation for my school garden, since this season, we get water for about 30 minutes in the morning through a tap that is “always open.” The water that comes has some pressure...
  32. ConnorJohn

    Question about lifting water through a water pipe

    Hello! First post, hope you all can help me out. I’m a peace corps volunteer in Nepal and am trying to implement drip irrigation for my school garden, since this season, we get water for about 30 minutes in the morning through a tap that is “always open.” The water that comes has some...
  33. Q

    Water cooling for trout ponds in the South African summer

    Hi I am is desperate need of advice, I live in sunny South Africa have 10 trout dams on an estate for catch and keep purposes. Each dam is approximately 2,5 Acres and 3 metres +/- 10FT deep in certain areas. The main issue is in summer the water temperature is sitting at 28deg celsius 82...
  34. Moayd Shagaf

    Equation for Water Flow Over Pipe Circular Hole

    suppose a water falling from pipe that above the ground with 5 meters, what is the equation that describe the level of water ( h) from pipe the hole at every moment of time? consider the pipe hole is circle .
  35. NoahCygnus

    Calculation of the change in internal energy of water

    Homework Statement If water vapor is assumed to be a perfect gas, molar enthalpy change for vaporization of 1 mol of water at 1 bar and 100 C is 41 kJ/mol . Calculate the internal energy, when 1 mol of water is vaporized at 1 bar pressure and 100 C. Homework Equations $$\Delta U = \Delta H =...
  36. P

    Testing Accuracy of a 0.25 Water Manometer Using a 10:1 Inclined Mount

    I need to test this gauge. It reads -0.25 to 0 to +0.25 inches of water. I am using it in the 0.02 to 0.03 negative and positive ranges. What of known value can I use to deflect this gauge maybe .1 or .05 in either or both directions to test the gauges accuracy? it gives the option of selecting...
  37. F

    Pumping Water -- Please check my pump system design work

    Hey Folks! Just need a quick sanity check ... Putting in a new 4in well and submersible pump ... trying to wrap my brain around the "physics" of it ... Here is what I ***Think I Know*** : 1) The Energy required to move any given volume of water to ground level can be calculated using M*G*H ...
  38. sophiecentaur

    Confusion about ion exchange water softener

    I am about to have a water softener installed and I thought I should learn a bit about the Chemistry involved. There is loads of advertising blurb on the Web but very little precise Chemistry. I am sure someone here can help me with this. The basic softening process is fair enough with sodium...
  39. B

    How high can an object be ejected out of water?

    You know when you push a basket ball in the water and let it go. It goes back to the surface very fast and is expulsed from the water and goes above the water surface. Now take it to an extreme, you place a capsule of air at the bottom of the ocean and set it free, how high can it reach above...
  40. P

    Volume of water in a container

    Homework Statement A closed container is connected with a tube, water will enter the container via this tube. How would the amount of water in the container affect the pressure in it when water enters the container via the tube? Is this the same as changing the volume of the container (which...
  41. sophiecentaur

    What is it about water based paints?

    I was Nikwaxing my boots the other day. This is a water based wax emulsion and uses no solvent. How does it work - or rather why wasn't the water based approach always used? There are EU directives about paints that forbid the use of solvent based paints so even car bodies are (will be?) coated...
  42. FelixLudi

    What factors affect the heating time of a water bottle on a radiator?

    Hi, I didn't know whether or not to put this topic into general physics, classical physics etc. (correct me if I'm wrong on posting here) Basically I have a normal water bottle, 0.5 L (maybe a little more, up to 0.6 L but definitely not more) and I always heat the water bottle up on a radiator...
  43. P

    Water Velocity Question: Impact of Pipe Length on Flow Rate

    For a vertical pipe of water can the pipe length affect the velocity of the water? note: the water is flowing through this vertical pipe.
  44. Fig Neutron

    What caused the strange water leakage from a sealed jug?

    I wasn't quite sure what to call this thread or where to put it. I left a one gallon jug of water sitting in the kitchen floor. When I came back maybe 4 or 5 hours later there was a pool of water around the jug. I looked at the jug and found water slowly streaming out of the top. The jug was...
  45. HelloCthulhu

    Water as a dielectric. Is this video a good demonstration?

    I found, at least in my uneducated opinion, a very good demonstration of water as a dielectric. I understand that putting water in a bag will change the dielectric constant of the water in it somewhat, but I think the capacitance meter at least makes water's value as a dielectric visually...
  46. B

    Automotive Car water pump barrier to flow when off?

    When a car is parked and not running... is the radiator water (or coolant) pump totally shut that water from the radiator side can't enter the engine or in equilibrium (what's the exact term)? The water pump is a centrifugal pump.. does this totally shut the inlet and outlet from mixing so that...
  47. E

    Why does entropy increase when hot water is mixed with cold?

    Why is entropy lost by hot water less than the entropy gained by the cold water?From perspective of energy,why is it better to take water and heat it to a temperature than it is to mix hot water and cold water to get a particular temperature.
  48. Space_Girl

    B Life Outside Our Planet Without Oxygen and Water

    Hello everyone :) I have a question.Is it possible for life to exist in other planets without oxygen and water? I mean just because we need it to survive here on Earth.It doesn’t mean all planets need it to support life as well.
  49. B

    Thermal Neutron Absorption Rate in Water?

    Homework Statement "The 2200 m/s flux in an ordinary water reactor is 1.5*10^13 neutrons/cm^2*s. At what rate are the thermal neutrons absorbed by the water?" Homework Equations (unsure) The Attempt at a Solution I know that absorption of a thermal neutron (a neutron in thermal equilibrium)...
  50. yecko

    ODE problem -- Find the amount salt in the tank as water flows through it

    Homework Statement A tank originally contains 100 gal of fresh water. Then water containing 1/2 lb of salt per gallon is poured into the tank at a rate of 2 gal/min, and the mixture is allowed to leave at the same rate. After 10 min the process is stopped, and fresh water is poured into the...
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