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. K

    How Does Refraction Affect Perceived Fish Size Underwater?

    From This picture, I think the fish will be smaller but the problem is how small will it be? (Fish "L" is the image of fish "K") Let ##H## be the depth of fish "K", ##\theta## be the angle of eyes to y-axis and ##n## is the index of refraction of water.
  2. T

    Child going down a water slide (potential energy and energy conservation)

    Vf = ? y = ? ME = mgy + 1/2mv^2 ME = 56*9.81*y + 1/2*56*1^2 Ui + Ki = Ui + Ki gyi + 1/2vi^2 = gyf + 1/2 vf^2gyf = 1/2vf^2 vf = 5.425 m/s 9.81y + 1/2*1^2 = 9.81*1.5 + 1/2*5.425^2 y = 2.949 m MEi = 56*9.81*2.949 + 1/2*56*1^2 MEi = 1648 J The picture for this problem really confuses me. I am...
  3. A

    Hydrostatic Pressure in Freefalling Water Tank: Comparing Point A and B

    tank with water is pushed from construction into freefall, A is at 0.1m depth B is at 10m depth (so manometer will show aprox 1bar of hydrostartic pressure when tank is at rest on construction) from 0-5sec tank is accelrating,after 5sec tank is falling with constant speed..1)is hydrostatic...
  4. K

    Buoyancy force when a ramp is under water

    So I have made force diagram And I think that I should find the acceleration by using these equations: ##\sum Fx=w\sin(15)-f_k-T_{x-buoyancy} ## ##\sum F_y=N+T_{y-buouancy}-w ## I know that the volume of water displaced must be ##V=\frac{1}{2400}m^3## and the mass of the water is then...
  5. Rub3y

    How much liquid water do I need to get a relative humidity of 10%?

    I need to calculate how much liquid (mass) could cause a relative humidity of 10% in a pipeline. The pressure in the pipeline is 38 barg and the temperature is 105 °C. I calculated the partial pressure of the water which would be 3,74 bar (with formula relative humidity and antoine...
  6. C

    Trig type question -- Speed of sound in water and in air

    unsure
  7. S

    Is there a property that defines how much water a hygroscopic salt can absorb?

    Is there some property that I can look up which would tell me how much water a hygroscopic salt can absorb (per unit mass of salt; for example anhydrous lithium chloride) before it's saturated and won't absorb any more?
  8. loophole

    Water deformation subjected to ultrasound waves

    Hello everyone, in one of my projects I am dealing with the following problem: We have a tank filled of water. If we assumed that a focused ultrasond beam hit the water perpendicularly to the surface. How can I calculate the displacement of the water surface? In particular, I am interested in...
  9. jaumzaum

    Why can shock waves condense water vapor?

    Why can a shock wave condensate water droplets in the air and produce the visible vapor cone that we see when objects move faster than the speed of sound. Also, does this condensation happens only when the object is moving with a velocity greater than sound velocity? I don't understand the...
  10. kyphysics

    If My Water Heater Doesn't Work, Is Water Still Safe to Drink (if Cold)?

    My water heater has an issue. I still get cold water, but is that safe to drink if the water heater is not working? Thanks!
  11. lucas pentland

    Net forces on a boat (propulsion, water and air resistance)

    2500 N [south] + 3200 N [south] = 5700 N [south] 5700 N [south] - 6000 N [north] = 300[north]
  12. A

    Vapour pressure of water vapour in air

    Vapour pressure in a closed system. Why does the partial pressure of water vapour in air equals to the equilibrium vapour pressure of liquid?
  13. M

    Water in a tank being driven up and down

    Hi PF! Suppose I have a square tank of water. If I drive the tank of water such that it's height as a function of time is ##h(t) = \cos(t)##, ignoring gravity, is this the same thing as saying the tank is holding still but the pressure field is changing as ##p(t)=\cos(t)##?
  14. cheekyhouidini

    Mass of water given only power and density

    Cannot figure out where to start, apart from maybe something to do with specific heat capacity of water?
  15. HelloCthulhu

    Arcing during water bridge, which dielectric breaks down first?

    I've been interested in the effects of electric fields on water for a while and came across this impressive demonstration of the water bridge experiment: The thing that fascinates me the most is how much the electricity arcs out of the water. For example at timestamp 8:43 the arc clearly goes...
  16. J

    Shouldn't the water have evaporated by now?

    It's a decanter that we used for some wine a week ago. After rinsing it out and letting it drain I set it upright in the window box so that it could dry. The sun hits it every day. It's been a week and still the condensation is there. It's got a narrow opening, sure, but still... shouldn't it...
  17. T

    Thermodynamics -- Calculations for heating water up

    A thermal flask with water of temperature 90c is placed out in room temperature 20c, sealed. How long before it reaches 55c? outer radius and height: 5cm, 25cm volume of water is 1litre. R = 0.5 Km2/W using this equation to solve it combining these two and integrating with respect to T...
  18. P

    Pressure required for water discharge

    Hello everyone, I am very interested in knowing the relation to determine the pressure required to push the water upstream. In the attached picture, water is filled inside a tank of volume V and air is constantly flowing inside the tank through an inlet with constant flow rate M. Water should...
  19. Adesh

    Oscillation of a boat in still water (Metacenter and Center of Mass)

    Let’s say we have a boat whose longitudinal axis is the y-axis (which goes into the screen in the figure below) standing upright in a still water . ##S## is the Center of Mass of the boat and ##C## is the Center of Mass of the displaced water.On ##S## lies the force ##\mathbf W##...
  20. gaurav_samanta

    Can hot water cool down through radiation?

    I have two more questions:- (1) Can we calculate the time it takes specifically for water to radiate all its heat? (2) Heat is illustrated as kinetic energy of molecules, so why collision between particles should result in the conversion of kinetic energy into radiation. Why conservation of...
  21. I

    Question about thermal physics -- Ice cubes melting in water

    First, I calculated the heat required for the ice to melt: Q=mLf Q=0.150×330 Q=49.5 J Then, I calculated the final temperature of the water by forming the following equation: Q=mcΔT −49.5=(0.15+0.35)×4200×(Tf −80) Tf=80.0 degrees Celcius But the answer says 32 degrees Celsius.
  22. il postino

    Chemistry Equilibrium temperature of a water and ice system

    Equal masses of ice at –10ºC and water at 80ºC are placed in an insulated container and allowed to reach thermal equilibrium. Calculate the equilibrium temperature Data: Water(ice): 37,65 J/mol.K Agua (l): 75,29 J/mol.K ## Lf = 6011 J/mol ## I solved it this way: ## -Q_{l} = Q_{ice} ## ##...
  23. Yeahaight

    Steam = 100C -- how much steam got injected into the water to heat it up?

    I guess, firstly I have to calculate the heat that is needed. Q=c*m(t2-t1) I'm not sure what to do further from here.
  24. S

    Selecting the Right Water Pump: Considerations & Reference

    If I was required to select a water pump for either domestic use or industrial, what are the consideration that I should take care of while choosing? How can I select a suitable pump according to height? What power should be implemented? Anyway, a general question would be "What is a reference...
  25. P

    Water flow through a packed bed

    Suppose you have a cylindrical column filled with packed, irregularly shaped particles. The bottom of the cylinder is flat and closed except for an array of small circular holes, regularly spaced except for a ring around the edge of the bottom where there are no holes. So, holes everywhere on...
  26. L

    Can Bleach Water Get Into Microscopic Pores in Plastic?

    I have an odd question; do you think that bleach water, rubbing alcohol, or quaternary can get into microscopic pores in plastic? About 10 microns or less in size? Or is bleach water and others i listed to big of particles? Thanks
  27. D

    Physics Homework about using Electricity to Heat Flowing Water

    This is the question: You want to make an electric instantaneous water heater in which 5.0 liters of water flows past a resistance per minute and heats water from 10.0 ° C to 45.0 ° C. Calculate the magnitude of the resistance to use and the amperage. The flow-through is connected to 230V So...
  28. tanaygupta2000

    How to Solve the Non-linear Differential Equation in Radial Ink Diffusion?

    I assumed p(r,t) as p(r,t) = R(r)T(t) as Separation of Variables method. I got the expression of T(t) as T(t) = C1eC2t and got a non-linear differential equation in R(r) as d2R/dr2 + (2/r)dR/dr - (C/D)R = 0 (I assumed r to be the radial distance in spherical coordinates) Now I'm not getting...
  29. brotherbobby

    Will the displacement of a solid ball affect the water level?

    (The picture below is my drawing. I followed the instructions of the problems and drew for reasons of clarity.) Let me start by writing down the given details : Volume of drum ##V_D = 0.05 m^3##, mass of drum ##m_D = 5 kg##, height of water column (initially) ##h_W = 1 m##, base area of water...
  30. Amitayas Banerjee

    How does water rise along a glass plate? (surface tension question)

    So, I was studying about general properties of matter and topics like surface tension. I came across the phenomenon of water rising along a glass plate like in the picture. I looked for some mathematical interpretation of this on the internet and in some books. [![enter image description...
  31. N

    What physics do I need to learn to do calculations for throwing water?

    How would I calculate the damage anything would take if a human were to pick up water and throw it? I would like to know this for a game idea I'm coming up with. I researched a bit online about certain physics that could apply (I.E: classical, modern, classical mechanical). I'm just not 100%...
  32. manareus

    Instrument name for water sampling and analysis

    Hello, thank you for your attention in my thread. I'm the head of Youth Science Club on one of the many High School in Indonesia, I got many members and I want to guide them for doing water sampling and analysis. In the history of my high school, no one is able to do water sampling and...
  33. vis viva

    Water, salt and a green Jello electret....

    I'm asking the question because I'm interested in learning more about how ionic compounds behave in and around electric fields. I'm not actually going to make the proposed electret. The color of the Jello is irrelevant, and Jello may not yield an everlasting electrect, so it's more about the...
  34. M

    Optical Laser to refract/reflect water vapor and smoke.... angles?

    Building visibiity sensor... What is best angle to detect water vapor reflection from laser, and refraction? I plan to have two open cylindrical containers painted flat black and put inside each other so the overlap is about 0.5-1" (adj to limit ambient light vs airflow). Laser is cheap red...
  35. Make it glow art

    Object magnified inside a cylinder of water

    Would you able to tell me what’s the ideal angle Of a curved glass in order to Magnify an object inside an aquarium to the maximum. Also what would be the ideal distance of the object inside the aquarium. Sorry if I didn’t explain myself properly. I‘m hopeful somebody would be able to explain it...
  36. tommyhp2

    Chemistry Understanding Bonding Energy in Water for Electrolysis Calculations

    Hello everyone, I'm just doing a bit of review of math to be used in electrolysis calculations. From the reference: https://www.ccmr.cornell.edu/wp-content/uploads/sites/2/2015/11/Saucedo_Skyler_splitting-water-with-electricity.pdf the result for r12 on page 4, the author has 1.5 * 10e-11 m...
  37. sabenabe

    Water stream projection distance calculation for different nozzle shapes

    Hello, I have built a device and i want to test different types of nozzles. Problem is; the size of the nozzles i need are hard to find in company stock. So i need to make sure before i make any order. I have no background or degree any related area so it is hard to understand the equations...
  38. L

    Entropy change for two masses of water mixed adiabatically

    the entropy change for a reversible adiabatic process is zero as it remains constant. Is this a reversible process? assuming T1>T2: hot (h) water has mass M, temp T1 cold (c) water has mass nM, temp T2 let the final temperature be Tf if δQ=0 as the process is adiabatic, |Qh|=|Qc| so Qh=-Qc...
  39. C

    Does the resistance of a material vary when introduced into water?

    Suppose we have a copper wire, of resistance R, and we introduce it in water, when applying now a certain potential difference between the two ends, will the intensity that circulates through the wire be the same, and therefore also the resistance ?, is there going to be a potential drop due to...
  40. fRod57

    How can I make a simple inductive MHD thruster in water simulation?

    Homework Statement:: Simualte the behaviour of water around an mhd inductive thruster Relevant Equations:: https://www.comsol.fr/paper/download/45837/Pintus.pdf Where can I start this simulation ? What is the required software ? [Mentor Note -- thread moved from the technical forums]
  41. K

    Buoyant force and a water column

    Recently I viewed the Searaser video at After watching it, I feel the numbers given in the video could be wrong but not sure. So I'd like to know how I can calculate the amount of water pushed by the Searaser device at some height in one wave shot e.g. at 100 ft, 200 ft and 300 ft above sea...
  42. brotherbobby

    Water flowing out of a tank through a hole

    I assume the water to start flowing from rest at position 1, hence ##v_1 = 0##. Applying the continuity equation, ##A_1 v_1 = A_2 v_2##, we find the (wrong) result that the velocity at position 2 is ##v_2 = 0## also! (We assume that ##A_2## is small but finite) Hence, to answer the question...
  43. brotherbobby

    Weight of water with objects floating

    We understand that the crucial thing about the problem is that the volume of water present in the three containers are not the same. Also, we note that in each case the weight of the container is the total weight of its contents. (A student might be confused as to why should be so - after all...
  44. Harini Krishna

    Calculating the speed of sound in water

    Hi,i want to calculate the speed of sound in water Containing Chlorine : 4mg/L in 1L distill Water Chloroamine : 4mg/L in 1L distill Water Florides : 0.5mg/L + in 1L distill Water Copper : 0.005mg/L + in 1L distill Water Lead : 1.3 mg/L in 1L distill Water Can you please help in...
  45. C

    Schematics of a high pressure water switch

    Does anyone have internal schematics (or illustration) how this thing work inside? Like how water flow can activate the conduction to the two wires connected? https://www.amazon.com/dp/B01MU3KQCD/?tag=pfamazon01-20
  46. T

    Why does water freeze differently when leaves are present on a shelter roof?

    Hello! I wait for the tram in a shelter. The roof of the shelter is made of transparent material (glass like). Leaves fall onto the roof and remain there in early winter during the first freeze. If there are no leaves on the roof (recently cleared by wind), the ice freezes with no...
  47. E

    Deriving the electrostatic pressure of a water droplet

    I assumed a uniform distribution of charge within the droplet such that ##E = \frac{q}{4\pi\epsilon_{0}r^{2}}## at the outside surface. I then said that the pressure acting at the surface would be the force on a charge element ##dq## within an area ##dA## on the surface, divided by the area...
  48. brotherbobby

    Gauge pressure of water oozing out of a pipe

    Assuming water to flow out of the pipe with the same speed as inside and the thickness of water column ##h_{ab} = h_{cd} = h##, my answer would be ##\mathbf{(P_b = P_c) > (P_a = P_d)}##. My reasoning is as follows : at positions ##a\; \text{and}\; d## the gauge pressure is 0 and the total...
  49. V

    Water level in a submerged closed vessel after it is turned upright

    Hello all, I need Your help with one real / theoretical situation. We have submerged pipe filled with air at atmospheric pressure that is closed on both ends. The hole is formed on one pipeline end and the water starts flooding the pipe. Let's assume pipe is tilted somewhat and that no air...
  50. bigyabbie

    Plumbing Compressed air powered water pressure

    Hi there, I have a few interesting problems that I have been exploring for a while now, but i quickly get beyond my level of knowledge of physics, so wondered if members of this Forum may be able to assist. One of the projects that we have been trying to solve is how to maintain a decent quality...
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