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. J

    Water sometimes drips from the exhaust of a running car....

    Homework Statement You may have noticed that water sometimes drips from the exhaust of a car as it is running. Is this evidence that there is at least a small amount of water originally present in the gasoline? Homework Equations not sure if there is one. The Attempt at a Solution I'm not...
  2. B

    What is the difference between water power and turbine power

    What is the difference between water power and turbine power? Do they have the same formula?
  3. T

    FEA for Water Tank: Weight & Pressure Analysis

    Hi, I'm trying to do some stress analysis on a tank filled with water, I have split the walls into sections and applied the appropriate pressures. However, I'm confused as to whether I apply the weight of the water+pressure at that height difference to the bottom of the plate; or will the...
  4. SherLOCKed

    Increase in the frequency of sound in a glass of water?

    Suppose you have a glass of water, and you beat a spoon on the bottom layer of glass through the mouth of glass, repeated beatings in a regular fashion will cause in increased frequency of sound produced due to the spoon beating?What causes such increase in frequency?
  5. P

    Deriving the Equation for Average Water Mass Flow Rate in Water Rocket Launches

    Hey, I'm a student who has to complete a written assignment for physics. I chose to launch water rockets and investigate the effect of volume on the range. I am trying to also come up with a mathematical model however I am struggling to understand an equation I found the following equation to...
  6. A

    How to make my Kelvin's Water Dropper work?

    Hello, I've made a version of Kelvin's water dropper for a school project, but it is not charging up. I've made the supports with PVC and the base with plywood. The water collectors are placed on Styrofoam blocks and the water flows through holes made in 2 plastic bottles. The inducers and...
  7. Jed K

    How does water vapor in the atmosphere form under normal conditions?

    So I understand generally how humidity in atmospherics work but there's this one thing I can't reconcile with the fundamentals. First, my understanding of the basics. Water boils at 212 F @ 14.7 psia (1 ATM). At 213F @ 14.7 psia that water is now 1F superheated vapor. So we're all on the same...
  8. B

    How to calculate the speed of a cross flow water turbine?

    How to calculate the speed of cross flow water turbine? Help, I'm struggling on our machine design.
  9. Boltzman Oscillation

    How does a the vertical force of gravity end in horizontal motion?

    When a stream of water falls perfectly vertical, some water hitting the surface will disperse horizontally. What is the force that causes this? References would be awesome!
  10. J

    Unsteady flow of water being discharged from a tank

    I am currently modeling the altitude that a water rocket can attain. In order to do this i am first modeling the the thrust phase. Due to the water mass decreasing with time (the same goes for the pressure - it decreases over time as the water is expelled out of the nozzle). This is an...
  11. M

    Measuring TDS of Filtered Tap Water: An Amateur Scientist's Guide

    I am an amateur scientist interested in all fields of science. What voltage potential is used to measure the EC of water to approximate TDS of filtered tap water?
  12. NTL2009

    42% of Sea Level rise due to human water use?

    I was surprised to see this in a 'pop science' article a few years ago ("Ask Marilyn"), but quickly found the source, which appeared reputable (to me). But I have not seen any follow up. I finally got back to it. https://www.nature.com/articles/ngeo1476 To stay within forum guidelines, please...
  13. fluidistic

    B Does a Black Hole with Lower Density Than Water Float or Sink?

    Would a black hole whose density is lower than that of water, sink? The answer is likely over my head. So far, I've found 5 answers by "experts", with quite different opinions. For instance on this website, one reads . On IRC I was told by another expert that it would sink. Here are the...
  14. S

    Ice Melts: Examining the ΔU, w and q of 0oC Water

    Homework Statement The first law of thermodynamics may be expressed in the form: ΔU = q + w, where ΔU is the increase in internal energy, q is the thermal energy supplied to the system, w is the work done on the system. Is ΔU, w and q positive, negative or zero when ice melts at 0oC to give...
  15. C

    Answer: Terminal Temperature of Water with Ice Cube

    We have a glass containing 0.5 liter (0.5 kg) of water whose temperature 100 degrees Celsius. We also have an ice cube with mass 0.01 kg and temperature -10 degrees Celsius. The cube is put into the glass. The glass is then insulated from the outside world, until the cube has melted. What will...
  16. Delta2

    B Mars Water: The Truth Behind Its Blue Color and Recent Discovery Revealed

    I guess water in Earth , in big lakes or seas, looks blue because the Earth's sky is blue and the water's surface reflects the sky. Now if there would be some big lake of water at Mars, how the water surface colour would be? I guess the colour of Mar's sky which is red (right or wrong?) It is...
  17. F

    I Liquid water reservoir reported under Mars polar cap

    The analysis is based on 29 radar profiles collected between May 2012 and December 2015. The identified region is about 20-km wide. The report acknowledges the results are consistent with with water or water-laden sediments. A brief discussion on the BBC (with no citations) asserted that...
  18. Gregs6799

    Need to find out the velocity of water

    Homework Statement 3kg/s of fresh water traveling through a pipe of 40 mm, I need to find out the velocity in m/s Homework Equations I have tried the equation: 3 / 40The Attempt at a Solution 3 / 40 = = 0.075m/s But not sure if I have to covert 3kg/s into another value before entering the...
  19. Jehannum

    Cause of water pressure in pipework

    Am I correct in saying that water pressure (in typical domestic heating system pipework) is achieved by deformation of the pipes rather than compression of the water? I believe water to be virtually incompressible, so the 3 bar (or whatever) pressure must come from the elastic stretching of the...
  20. T

    Air-powered water balloon launcher, Which weights to use?

    Hi all, first post. Bare with me. I've got a simple air compressor-powered water balloon launcher made using PVC. It works extremely well. But, I'm needing to make some "sighting charts" to predict where everything will land based on angle, loaded psi, size of balloon---and the wadding...
  21. Monoxdifly

    MHB Calculate Water Pipe Surface Area & Volume - Ask an Expert

    A water pipe whose diameter is 84 cm dan length is 2,4 m can contain rain water with the water height 68 cm like in the attached picture. Determine: a. The surface area which gets contact with the water b. The volume of the water (in liters) So... How do I do? What is the simple way to...
  22. A

    A runner weighs 687 N and 71% of this weight is water. (a) H

    Homework Statement A runner weighs 687 N and 71% of this weight is water. (a) How many moles of water are in the runner's body? (b) How many water molecules (H2O) are there? Homework Equations n = N/NA n= m/mass per mole NA = 6.022E23 F=ma H: 2*1 O: 16 The Attempt at a Solution a) 687/9.8=70.1...
  23. Krushnaraj Pandya

    Motion of rolling metallic shell filled with water

    Homework Statement A metallic spherical shell of mass M and radius R is fully filled with water of mass M is set into pure pure rolling motion on a smooth horizonal surface (w clockwise, v to the right). Now water is freezed suddenly, and the ice sticks with the shell. What is- a) moment of...
  24. A

    Thermodynamics problem -- Find the mass of water that vaporizes

    Homework Statement Find the mass of water that vaporizes when 3.02 kg of mercury at 223 °C is added to 0.347 kg of water at 83.4 °C. Homework Equations Mercury Q = Water Q + Water mL mc∆t= mc∆t + mL The Attempt at a Solution mass of vapor = ((3.02)(140)(223-tfinal) - (4186)(.347)(change in...
  25. B

    How do I find an enthelpy value if my temp. is below 50 deg. celcius?

    I want to design a curding machine (Milk to Cheese) with an open system that operate at isobaric process (contant pressure), P = 1 atm = 1,... bar the range of temperature is = 25-75 0C can i find an enthalpy of water from Mollier Diagram if my temp. is 25 to 75 degree celcius ? how ? from my...
  26. Doruk Y

    How can we visualize the movement of Photons on the water?

    We all know that the photons have a wave-like motion,if the waves on the water form because of the motion of the particles inside the air(oxygen+nitrogen gas and %1 another gasses) so in the beginnig of this process,photons hit the air and make particles jiggle and that make air jiggle and air...
  27. I

    The acceleration of a bubble in water

    Hi, I have a question about a rising bubble. I read that the initial acceleration of a bubble (with negligible mass) in water is 2g, where g is the gravitational acceleration. I understand that if a bubble rise then the water move around it, but I can't derive this equation. Could someone help...
  28. Baris Kalfa

    Change of of the pressure of water inside a container

    I am having difficulty solving an exercise prepared by our professor for hydrodynamics. I am unsure if Laplace pressure is the correct way to calculate the pressure inside. It comes to my mind that I should've used the equation for hydrostatic pressure instead (##P=P_0+\rho gh##). However, the...
  29. S

    Motion of body in water under 7 bar pressure

    Is entering force will be same when a body enter in two box one filled with water and other filled with air. Both boxes have same pressure 7 bar and velocity of body at entering point is 9 m/s
  30. Ushitha Dissanayake

    How do I find the terminal speed of a body in water?

    Homework Statement A baseball has a terminal speed of 42 m/s in air (ρ = 1.2 kg/m^3). What would be its terminal speed in water (ρ = 1.0 x 10^3 kg/m^3)? A) 0.05 m/s B) 1.5 m/s C) 18 m/s D) 42 m/s E) 1200 m/s Homework Equations D=½Cρ*Av^2 where the magnitude of the drag force (D), relative...
  31. kristjan

    What is the thickness of the wall of a hollow iron sphere submerged in water?

    Homework Statement Hollow iron sphere is half submerged in water.Sphere has outer diameter of 10 cm. Calculate thickness of the wall , when the iron density is 7.9 g / m3. I get answer 0.11cm, book says that it is 0.22cm. Homework Equations [/B]The Attempt at a Solution First i found buoyant...
  32. T

    Estimation and validation of water pressure at nozzle

    ρ I am trying to estimate and validate the pressure of water exiting a nozzle. For an unknown reason, the validation is consistently twice as high as the estimation. Here the approach: Estimation: I am using the dynamic pressure equation for the estimation: q = 1/2 * ρ * u2 where, q = dynamic...
  33. Aun Muhammad

    Fortran 1D Shallow Water Wave in FORTRAN using LAX WENDROFF Method

    Hey everyone, I’m trying to simulate a 1D Shallow Water wave in FORTRAN using the Lax Wendroff Method. The case is fairly simple. I have a wave generator on one end of a water pool and a wall boundary on another. The waves start traveling towards the wall and are ‘reflected off’ the wall. The...
  34. T

    Water / steam homogeneous mixture

    We all here (I presume that members here have better understanding of physical processes than average person) know that it isn't a fact that water began to boil at 100°C but much before that. When being heated in an open pot, as the temperature rises, water began to boil and more and more water...
  35. T

    Why doesn't the temperature of water slightly decrease during boiling?

    When you heat a pot of water why wouldn't the water temp decrease slightly when it starts boiling? Isnt boiling a type of evaporation? In evaporation the molecules near surface have enough KE to escape into the gas phase, which then lowers the T of the remaining liquid. That is how sweating...
  36. F

    Static pressure in a water pipe system

    I have a problem where I want to find out the static pressure over a city in a water pipe system. As I know the elevations over the city I was first thinking of just using p = rho * g * h, but this should only apply if the pipe system were under water (if I use the density of water at least). So...
  37. H

    Resultant force from water on dam

    Homework Statement : [/B] The cross-sectional profile of a dam is shaped as an isosceles triangle. The dam is standing on horizontal ground and the watermirror is as high as the top of the dam. The dam has height h, length l and the distance from the bottom to the watermirror along the dam's...
  38. S

    Hydrostatics: Immersing a metal cube in water......

    Homework Statement A metal cube is placed in an empty vessel. When water is filled in the vessel so that the cube is completely immersed in the water,the force on the bottom of the vessel in contact with the cube (A) will increase (B)will decrease (C)will remain same (D) will become zero...
  39. Gabriele99

    Will water flow ever stop if we increase resistance?

    Complete question: Will flow ever reverse or stop if we increase resistance in this pipe scenario? There are 2 comunicating vessels. The highest vessel is coninuosly alimented with new water. Water in excess flows down on the sides. Water will try to reach the same height in both vessels, so...
  40. G

    Water tower: Why is all the water at the top?

    Hi. Most water towers store their water in a huge container at their top. Why? Wouldn't it be easier to place the container at the bottom and just add a long, thin pipe upwards to create the hydrostatic pressure? Is the problem that the container would need to endure too much pressure? Or that...
  41. AlaskaJoe73

    Design load of a water tube ride, such as on a cruise ship

    When designing the structure of an elevated water tube ride (water flows by gravity through a tube large enough to accommodate 2 people on a float, say 500 lb. max. and the volume of water is constant) how much effect does the object floating on the water have?
  42. Bikash Kumar Das

    I Relative Permitivity, Permeability & Refractive Index of Water

    How does the relative permitivity and relative permeability related to the refractive index of a dielectic medium like water?
  43. R

    Chemical terminology for an electron in water

    I've read several papers that talk about electrons in water, clearly they don't last very long as they react quickly with the oxygen. But I'm confused about the terminology they use, some call them solvated electrons, some hydrated electrons and others aquated electrons. I can't seem to find a...
  44. N

    If you threw a warm water balloon into space, would it boil?

    And by how much would the balloon expand, if at all?
  45. S

    Sanity check on falling steel ball in water

    Homework Statement What is the speed of a 5 mm steel ball falling through water at 10 C[/B] Viscosity of water: 1.3059 * 10-3 Pa*s (Various online sources) Homework Equations Laminar flow: Vt = gd2 (ρp - ρm)/18μ Vt = terminal velocity g = gravity (10m/s2) d = diameter of ball ρp =...
  46. K

    Calculating Velocity of Water Flow in Open Channel

    Homework Statement [/B] We have water flowing in an open channel. A small tube is placed in the channel, and the water raises to a height "l" above the water surface. The distance from the water surface to point 1/2 (points are at same height) is d. At point 1 the fluid velocity is V1 and at...
  47. J

    Pressure in the vessel containing water

    Homework Statement Homework EquationsThe Attempt at a Solution I think the pressure that the question is relating is the vapour pressure but I do not understand how that depends on the volume of the water contained in the vessel .Is there a relationship between the two ?
  48. J

    How does the density of water affect a sphere dipped in it?

    Homework Statement Homework EquationsThe Attempt at a Solution There can be two cases 1) The sphere might be a shell such that it floats on the water .When the temperature increases , even though density of water decreases , the force of buoyancy should remain same . Because force of...
  49. K

    Pressure on a vertical rectangular plate submerged in water

    The question goes as follows..: A car driver has an accident and drives into a lake. The car sinks to the bottom. The distance from the car door to the water surface is 10m. The car door is 0.9m wide and 1.3m tall. Assume that the car door can be approximated as a vertical rectangular plate and...
  50. NCBryan

    How can 10% ethonal gas produce 73% alcohol? (with water)

    I purchased 22.752 gallons of gasoline containing +- 10% ethanol dispensing it into a 23 gallon gas tank. Then I drove 23 miles (mostly up hill) to a job site. At lunch time I was not able to crank the engine. The symptoms were clear, it was water in the gas. I have a video if you want to see...
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