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

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25
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7answers
17k views

Why do tsunami waves begin with the water flowing away from shore?

A sign of a tsunami is that the water rushes away from the shore, then comes back to higher levels. It seems that waves should be both + and - polarized and that some tsunamis should go in the ...
2
votes
2answers
840 views

How much better is salt water at letting through microwaves than pure water?

Radio Wave Attenuation There are two general types of matter (substances) in the universe that affect electromagnetic waves, conductors and insulators which are called dielectrics by ...
1
vote
0answers
46 views

I need to remove water from a system [closed]

I work in an industry and I need to remove water from a system. The scenario: There is a washer and a blower on a conveyor belt. The item being washed is plastic (not sure what type) and can't be ...
0
votes
0answers
45 views

How can we describe or model the spread of ice during the freezing of the surface of a still lake?

Premise: I live in a place where it is unquestionably wintertime in every aspect of the phrase. I was driving down the street and I drove by a lake. There was a recent and sudden temperature drop ...
0
votes
0answers
19 views

Heating water with low and high gas heat

Similar type question is asked before but i'm looking for other aspect of it. I observed that if water is heated with low gas heat, it takes long time but it retains it high temperature for long time ...
3
votes
2answers
595 views

What air pressure is needed on mars, to have fluid water?

The atmospheric pressure on the Martian surface averages 600 pascals (0.087 psi), about 0.6% of Earth's mean sea level pressure. There is a lot of frozen ice on mars, but it can't melt, because of ...
0
votes
0answers
36 views

How much does grabbing a piece of a plane free falling change your survivial?

Just for context let's saying you are falling from a plane in free fall position at 56m/s(200 km/h or 120 mph) and you grab onto a wing which slows you down to 25m/s. You weigh 70kg. so ...
22
votes
2answers
2k views

When a drop of water falls into water, where do the splashes come from?

When a drop of water falls into a reservoir of water from a high enough altitude, water droplets will splash (image credit): My question: Does the water in those droplets come from the original ...
2
votes
2answers
174 views

Where would a perfect sphere break under pressure?

My roommate who studies physics once showed me the leftovers of an interesting experiment: They filled up those metal balls with water and then froze it. The water expanded and with all of its ...
2
votes
1answer
31 views

Would it actually be possible to preserve a snow flake?

In episode one of season 3 of The Big Bang Theory Leonard offers Penny as a gift a snow flake he says he preserved in some kind of resin, having it brought from the North Pole. Is this purely ...
1
vote
0answers
43 views

Bond Angle in a water molecule

I recently started up reaching up on the Feynman lectures on Physics and in Vol I,Chap 1-2,Feynman states that the bond angle between the hydrogen and oxygen atom is 105° 3′. I know that the bond ...
0
votes
1answer
96 views

What Is the Physics principle behind dropping a stone into a cup of water?

I have been doing an experiment about relationship between drop height of a stone and the loss of water in the cup it lands in. I found that after dropping the same stone into a cup with the same ...
3
votes
3answers
166 views

Why do square shaped cups spill easier than round cups?

I've noticed that when I use a cup that is square shaped with convex sides, it spills more easily than a circular cup. Why does this happen? What is the most spill-prone cup shape? What is the most ...
3
votes
2answers
530 views

Reducing the evaporation of water at room temperature

Water drops kept on different surface evaporate after a few minutes. How can I reduce the rate of evaporation of these drops? Can I add some additives which suppress evaporation?
4
votes
4answers
6k views

Why the shape of rainbow is semicircular after rain why not the whole atmosphere is colorful?

I have a very simple question. Everyone must have seen the rainbow after rain. According to the theory the rainbow is created due to the passing of sunlight from small drops of water in the ...
4
votes
2answers
100 views

Water level of ice in cup [duplicate]

Since ice is less dense than water, it floats on it, we all know this. Now suppose, if ice is floating in a glass cup, when the ice melts there should be some change at water level in the glass cup. ...
6
votes
3answers
211 views

Why is concrete dry around cracks?

On a warm and partly cloudy day this summer, I was sitting in my office and suddenly heard rain on the roof. I went outside to shut my car windows. By the time I did that and was walking back into ...
2
votes
2answers
1k views

How much water must flow trough canal to maintain a constant water deep?

In order to maintain a constant water deep in canal, how much water must flow trought the pipe ? As shown on picture, canal have a rectangular shape. I don't know if canal length have an influence. ...
1
vote
0answers
223 views

How can I bring water to 90 degrees C? [closed]

For my coffee I need the water to be 90 degrees Celsuis. Boiling water, however, is 100 degrees. How can I make it 90 degrees? Do I just measure the temperature of the water from my tap, and if it's ...
1
vote
1answer
52 views

How do you work out the energy requirement for a submerged pump?

I was wondering if you were to place a pump in a submerged container and then were to open a hatch allowing water to flood the previously vacant cavity how much energy would be required to discharge ...
7
votes
1answer
301 views

Electric Field Change Freezing Temperature of Water?

I assume that the reason water freezes is because as you decrease the temperature, the kinetic energy of the water molecules decreases and the dipole bonding potential eventually over comes the escape ...
6
votes
4answers
3k views

Effect of water pressure on sinking objects

As I understand, water pressure increases as we go towards bottom of the ocean. So if an object* is thrown into water and it starts sinking with some speed, does the sinking object's acceleration ...
1
vote
0answers
22 views

Will Ice Cubes Form Quicker when Made from Hot Water or Cold Water? [duplicate]

When you put water in the freezer you can make Ice Cubes. But does the time taken for these Ice Cubes to form decrease or increase when the water which is used is hotter or colder?
-7
votes
2answers
564 views

Are shadows underwater “wet”? [closed]

Sorry if this is the wrong place to post this but it seemed the most appropriate. I read a riddle earlier today that mentioned something about shadows underwater and it got me thinking.. Would a ...
10
votes
2answers
317 views

Can cannonballs go through water?

In the recent Spielberg/Jackson Tintin movie, there is a scene where Red Rackham and Captain Haddock's ships are fighting, and cannons are fired. The cannonball is shown at one point to go through a ...
-1
votes
1answer
629 views

What happens if we put a pinch of salt on the ice cubes which is melting in the water?

What happens if we put a pinch of salt on the ice cubes which is melting in the water? How will the ice react to the salt, and what other things will happen after mixing them?
1
vote
2answers
236 views

Why does room temperature water and metal feel almost as cool as each other?

From what I've read about heat, temperature and conductivity, I understand that the reason water at room temperature feels colder than most other things at the same temperature (like wood, air, ...
0
votes
2answers
89 views

Why are ripples formed in water round? [duplicate]

Despite whatever be the shape of object that you drop in water, it be 1D, 2D, 3D, they all produce ripples in a circular pattern, is this pattern followed under water as well (in terms of density ...
1
vote
2answers
132 views

Why Does Air Hold More Water When the Air is Warmer?

I know that when the temperature of the air rises, the maximum amount of Water it can hold before the water condenses to water droplets increases. But why is this - has it got something to do with ...
6
votes
0answers
80 views

Why is the splash of water always vertical, no matter in which angle the gunfire hits the surface

When gunfire hits the surface of a pond, the water seems to always splash directly upwards, in 90° to the surface of the water, no matter at which angle the gun is fired. The angle is usually very ...
2
votes
2answers
179 views

What would a graph of temperature increase of a cup of water in a microwave look like?

My lunch had been in the microwave for a minute or so, and I was wondering if I took it out 10 seconds early, would the amount of temperature it increased in that 10 seconds be more significant, less ...
9
votes
4answers
21k views

Why does ice have a lower density than water?

Can someone explain me why is ice lighter than water? As I know, all solids are usually heavier than the liquids (correct me if I am wrong).
5
votes
1answer
67 views

How does the movement of molecules change at the edge of a liquid?

I am thinking about how the velocity of molecules measured from a small region of space might change as the region of inquiry moves closer to the edge of a container. Ultimately I am thinking about MR ...
5
votes
1answer
110 views

Superhydrophobic coating and water friction

If you were to apply super-hydrophobic coating to the hull of ships or even submarines, would you get more or less water friction? If the coating completely repels the water you could argue there ...
0
votes
4answers
67 views

Is it true that water go down the drain counterclockwise in the northern hemisphere and clockwise in the southern [duplicate]

Many websites say that water drain in different directions in Northern, Southern hemispheres. Some people say that Coriolis effect causes it. Some people say that it's not true.
1
vote
1answer
35 views

What concepts/rules apply for multi-stage pumping of water

For single stage (ie one pump) water transfers calculations for pressure loss are commonly done by adding the elevation difference of the start and end of the pipe line to the friction losses that ...
2
votes
1answer
96 views

Water behaviour under theoretical near-infinite pressure conditions

I've asked a similar question here but the answer given shows the behaviour of water under general conditions. I'd like to know what the behaviour of water is like as pressures increase towards ...
4
votes
2answers
193 views

Why do power lines buzz more when it is low-humidity outside?

I have observed that the power lines buzz louder when there is less moisture in the air. Why is this? If it will help the lines are located on the foot hills of a nearby mountain.
0
votes
2answers
42 views

why only surface of water get frozen in polar countries?

why only surface of water get frozen in polar countries? but if i kept glass full of water in fridge then not only surface, whole water turns frozen ,why?
4
votes
3answers
5k views

Why should fluids be confined for Pascal's Law to be applicable

When is Pascal's law about fluid pressure propagation applicable? Is it applicable to a closed circular pipe with a pump rotating the fluid, but not to a tub of water. Most statements require only ...
1
vote
1answer
209 views

How does underwater sound sound?

I have been thinking about underwater sounds (i.e. sounds produced and recorded underwater), what exactly the water does, and how to emulate this effect. Imagine a sound played underwater (e.g. from ...
4
votes
1answer
128 views

What is the effect of water 'climbing' over a cup via a wet string? [duplicate]

I have noticed (with tea bags, etc) that if you get the whole string wet, and you have one end inside the cup and the other end below the level of the liquid (outside), the water drains down the ...
6
votes
5answers
8k views

How far can water rise above the edge of a glass?

When you fill a glass with water, water forms a concave meniscus with constant contact angle $\theta$ (typically $\theta=20^\circ$ for tap water): Once you reach the top of the glass, the water-air ...
1
vote
2answers
78 views

How much entropy is produced in evaporating water due to irreversible evaporation towards equilibrium (humidity=100%)?

$dS=dH/T_{boil}$ for the increase in entropy by changing a phase at saturation ($T=373\text K$ for $p=1\text {atm}$ for water). However, water also obviously evaporates below boiling point when ...
0
votes
1answer
2k views

HEPA vs. water filter in vacuum cleaning [closed]

What is the difference between air being filtered with HEPA or water? Which one performs better within a non-allergic home environment? Does water filter have a meaning still when common vacuum ...
2
votes
1answer
733 views

Does increasing diameter of a water pipe increase speed or volume?

Let's say water is flowing from an arbitrary Source to some arbitrary Sink via a small pipe: I'm curious as to what actually ...
2
votes
1answer
450 views

How to calculate the volume of water in a certain amount of air, given the relative humidity?

If, according to the weather forecast, the current humidity is 90%, how can I calculate the volume of water that could be extracted from a certain volume of that air?
30
votes
7answers
5k views

Is it possible to “cook” pasta at room temperature with low enough pressure?

It is known fact, that boiling point of water decreases by decreasing of pressure. So there is a pressure at which water boils at room temperature. Would it be possible to cook e.g. pasta at room ...
30
votes
4answers
4k views

Why does water rise through a hole in ice

I've just been watching a doco where some guys cut a hole in a frozen lake, the ice is 3 feet thick, I was surprised that the water rose to the level of the ice. My friend assures me it's because ...
2
votes
0answers
110 views

Heat Transfer, Water in a pot

I have a question I've been pondering for a while. How can I determine the temperature in a pot filled with water? I know these things: I have a known mass of water, of mass $m_w$ I have a pot of ...