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

learn more… | top users | synonyms

1
vote
3answers
34 views

Pressure Drop in Water Fountains

In first grade, my class made a list of things that our school could improve on. One of the things on the list was to increase the water pressure in the drinking fountains because it was very poor and ...
0
votes
1answer
51 views

How cold does this ice have to be to freeze this water bottle solid?

We are at sea level in a room that is 21 celsius. We have 1 liter of sterile water with a temperature of 21 celsius in a normal plastic bottle. We have a 20 liter bucket of ice cubes, consisting of ...
2
votes
1answer
40 views

How could water pour out from upside-down bottle, unless its pressure is smaller than atmosphere pressure?

Just a simple question : when we remove a stopper of an upside-down bottle, water flows out. But the pressure caused by the mass of water's column is usually smaller than atmosphere pressure unless we ...
1
vote
1answer
36 views

The colour of clouds

Clouds can be a variation of grays, from white to some dark gray, almost black. They are clearly grayscale, so it means they reflect all colours uniformly, but some clouds are whiter than others, so ...
0
votes
2answers
53 views

What is the nature of equilibrium between water and air in a sealed container that is heated above 100C?

In the case of a single substance (water), looking at the phase diagram is enough to conclude what happens upon heating: (source: WolframAlpha) But what if I have water and air (or some other gas) ...
1
vote
1answer
23 views

The thickness of a puddled sheet of water

If I pour water of different amounts into a puddle on a level surface, it appears by eye that both puddles have the same height. The water seems to retain itself into a puddle by surface tension. I ...
3
votes
0answers
36 views

Chemistry of water under pressure [closed]

What is the structure of water under extreme pressure, like the bottom of the ocean on a moon like Europa.
4
votes
1answer
33 views

Will water cool faster in an earthen pot if wetted externally?

If we put water in an earthen pot then water is being absorbed and it reaches the surface of the pot and then water evaporates and makes inside water cool. So is it right that if we wet the earthen ...
1
vote
1answer
13 views

Lengthening in-flight evaporation time of water droplet in air

How one can increase the in-flight evaporation time of sprayed water droplets in air without changing the thermodynamic conditions of the ambient air ( i.e. RH, T ). For instance mixing water with ...
3
votes
1answer
55 views

Why is it easier to remove stains with water?

And I don't mean stain removers, but literally tap water. See here's the thing, you can't remove a stain without some sort of friction, and water reduces friction. Yet if I say, spill some coffee and ...
1
vote
4answers
45 views

How can removing energy from a system do work? (ice)

Water freezing into ice expands, damaging roads, breaking rocks, etc. To my understanding, this is doing work (in a physics sense) by removing energy from the system. How is this possible?
0
votes
0answers
29 views

How can I get the exit temperature of water entered 100 degree in a pipe surrounded by 30 degree water?

Assume any value for: Length of the pipe The material of the pipe Velocity Heat transfer coefficient. I tried considering it as parallel flow heat exchanger but the water in this example isn't ...
2
votes
0answers
49 views

How fast should 6 liters flow out of the sink through a 6cm pipe?

I had 6 liters in the sink when I pulled the plug. It took the water about 30 seconds to get through a pipe which has about 5cm in diameter. I think the pipe might be blocked a bit, causing it to have ...
0
votes
0answers
19 views

Role of heat flux on bubble size

This is sort of related to this question, in that the question was spawned from the same question on Worldbuilding. Say you have a relatively shallow open pool of water (a pot or pan). When the ...
0
votes
0answers
26 views

Water in pot with a heat source beneath it to boil it, does the water move?

I mean if there is there heat transfer by convection in the water? since convection requires motion. if it moves, then how can i determine the velocity of the water?
7
votes
2answers
258 views

Does the size of bubbles in water brought to a boil ever vary as a function of the amount of water?

Some discussion surrounding this answer on Worldbuilding got me curious. When water is brought towards a boil, bubbles are formed. Anyone who has ever cooked anything whatsoever knows about this. ...
1
vote
1answer
40 views

Is it possible to fight tree height limit with centrifugal force?

I heard tree has some height limit because water cannot be pumped over some height (130m if I remember it right) which cap the limit of tallest tree possible on earth But there are centrifugal force ...
0
votes
1answer
40 views

Thermofluid mechanics, calculating load on a steel water tank

An open cylindrical water tank 2.4m diameter rests on three legs evenly positioned around the periphery of its circular base. The base and sides of the tank are made from steel with relative density ...
-5
votes
1answer
44 views

What phase is water at 262C and 15bar? [closed]

what phase is water at 262C and 15bar? at which conditions and above can we be sure that the water is totally gaseous? can I see a water phase graph for 262C and 15bar?
0
votes
2answers
44 views

Will it sink under circumstances? [closed]

I'm a 10 year old with a question. If you have a waterproof box the shape of a prism with an open top and you have a lid that fits perfectly in the top and you fill the box with water then put the lid ...
1
vote
2answers
45 views

Why water's temperature is less than air?

I measured the temperature of water and found that it's less than room temperature. I think evaporation is the main reason of it. Are there any reason except evaporation for the less temperature of ...
3
votes
1answer
69 views

Fluid Mechanics Paradox

This is a deceptively simple problem in fluid mechanics that I can't quite figure out because it produces a paradox. Suppose that there is a straw and a small column of water inside the straw, such ...
-1
votes
1answer
48 views

The physics of a drying shirt

So, I've noticed this enough times to state my observations. I wash some shirts and hang them up to dry. Sometimes I need to wear one before they have completely dried. What I have noticed on ...
1
vote
3answers
33 views

Heat transfer between water tank and room temperature

I have 20 gallons of water (salt water, but this might be irrelevant). These 20 gallons have a heater that maintains a minimum of 78º F. With the increasing temperatures during summer, the water ...
2
votes
2answers
73 views

Submerged water jet

I am trying to calculate at what pressure and speed water from a high pressure water jet will hit an object 100 millimeters away from the nozzle opening, but i can't figure it out. The nozzle will ...
1
vote
1answer
36 views

D2O distribution in water [duplicate]

I just learned that about 1/1000 of hydrogen is deuterium. Does that mean 1/1000 of water is D2O, which is heavier and sinks to the bottom in a glass of water? And consequently is there a layer of D2O ...
1
vote
1answer
75 views

Would a world filled with water collapse?

I don't know if this is considered off-topic but, If you took a planet (assumed solid) and filled it with water continuously/non-stop what would eventually happen to the water? Would gravity at ...
0
votes
1answer
60 views

How long time before all the water in a lake has been replaced? [closed]

Studying hydrology, and in that context we've seen some information about lakes and the times it takes for the water to renew completely in them. This got me interested in finding out how this is ...
0
votes
1answer
35 views

How much salt to dissolve in water for a noticeable change in volume?

I am reading through this High School science lab about how dissolving salt changes the volume of water: Place 300 to 400 g of salt in the flask (1L) Pour in enough water to cover the dry salt, and ...
0
votes
0answers
15 views

Average Rate of Evaporation of Water

Consider a container of volume $V$ and cross sectional area (exposed to another fluid, say air) $SA$. The container is at constant temperature $T$, and contains $N$ molecules of water, where $N$ is ...
0
votes
1answer
38 views

effect of opening the barrier between a tube with one side pressurized and the other side a vacuum

What would happen when a tube with an air space pressurized to 500 atm by the water exerted at 5 km below the surface was opened into a vacuum chamber rising up 5 km to the surface? The bottom of the ...
1
vote
1answer
37 views

Surface tension in a balloon wtih water [duplicate]

Imagine such situation: We have an empty balloon. We put a long, narrow tube into this balloon and we fill it with water. Then, the volume (and surface) of the balloon will start to increase. The ...
0
votes
1answer
24 views

Can vaporization heat added to the whole volume of liquid before vaporizing it?

It seems, for example a volume of water is heated to boiling point, then part of the water is vaporized, while the remainder need much more heat to vapor, which means that part doesn't receive latent ...
1
vote
0answers
11 views

Why Flow meters are some times showing -ve fluctuating Values in Pressurized Pipe lines [closed]

In our Underground Water reservior we are pumping water by Hydro-pneumatic pumps to maintain same pressure till last connection. in order to measure the flow we have installed precise electromagnetic ...
18
votes
3answers
2k views

Why does water feel cooler than air?

My first assumption was based on "evaporation causes cooling" but I realized that it is not the case as it is cooler even if I am submerged under it. Are all liquids generally cooler than air ? Just ...
-4
votes
3answers
49 views

H2O Fuel of the Future [closed]

So I was busy trying to solve the world's problems the other day and a thought crossed my mind. I came across some data about cars that run on H2O and I was thinking that this seems like a great way ...
0
votes
1answer
35 views

Optics of stationary waves

could anybody tell me how it Works if it comes to stationary waves created on the surface of water jet and optics? there are some crests and troughs which work like lenses, but if you have water jet, ...
6
votes
1answer
167 views

Melting ice: reversible or irreversible?

I am looking into whether the melting of ice (or any substance for that matter) at constant pressure and temperature is reversible or irreversible. Different sources say different things, and it may ...
1
vote
1answer
67 views

Water vs. Air : Heat Absorption/Capacity

I am not a physicist by any means and not even a current student, but nonetheless I am looking for an answer. Here is what I have gotten so far from university websites and other various resources on ...
1
vote
1answer
50 views

Noncoalescing and bouncing droplets

if you set a dish filled with water onto a loudspeaker or other vibrator and make vibration, When it oscillates, it is possible to hold small droplets on its surface for a long time. I mean, when you ...
0
votes
1answer
33 views

Water molecule Resonant Frequency

If water is subjected to microwave energy at the water's exact resonant frequency but 90 degrees out of phase, would the water molecule cease vibrating? Would the water then freeze or be cooled at ...
1
vote
2answers
64 views

Why Counter waves are being produced in water?

While studying water waves in a cuboidal tank, the following observation was made. A gentle tap on one side (A)of the tank, generated waves from that side towards the opposite (B). At the same ...
0
votes
0answers
34 views

What makes some air bubbles in water more persistent?

In a plastic bottle of water, near the walls, it is common to observe the presence of little bubbles (I would estimate them to be $\approx0.5$mm in diameter. In my experience, most of these bubble ...
0
votes
1answer
36 views

Pumping water vapor into liquid water [closed]

Do liquid water and water vapor count as different types of matter? How does Second law of Thermodynamics apply when I pump water vapor into liquid water? What would happen when water vapor goes into ...
1
vote
1answer
31 views

Why is water expelled more powerfully from a trigger hose the moment its triggered?

I think its something to do with acceleration but can't put my finger on it. Something about the most power needed as the greatest acceleration, as water flows up to full rate the accel and thus ...
4
votes
0answers
29 views

How does air going through silica gel change its humidity

Assume that the properties(temperature,humidity,velocity and so on) of the incoming air flow stay constant. The air flow goes through a silica gel plate. Humidity of the air will decrease, but how to ...
3
votes
0answers
44 views

Detect ions in water using impedance spectroscopy

I would like to check the presence of Na, Ca or other ions dissolved in water using impedance spectroscopy. I was thinking that because the ions have different masses they will have different ...
0
votes
0answers
19 views

How much power is being actually delivered by an electric heater to a cooking pan?

I've been doing experiments on an electric heater heating a cooking pan filled with 2 litres of water, from 20°C to 70°C; now I'm trying to draw a theoretical heat transfer model thath should match ...
1
vote
1answer
52 views

How does water height in a vacuum chamber effect pressure

I am testing for package leaks in non-porous packages. Quick details are: 1) Package is sealed at atmospheric pressure. There is some headspace inside the package which is just air. 2) A small hole is ...
0
votes
1answer
26 views

Why do water droplets not form on large openings such as pipes?

When you have an object with a small opening, such as a pipette, water droplets form and hang easily. However, when you have a larger opening such as a pipe, the same water droplets do not form. Is ...