Questions tagged [water]
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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How does water evaporate if it doesn't boil?
When the sun is out after a rain, I can see what appears to be steam rising off a wooden bridge nearby. I'm pretty sure this is water turning into a gas.
However, I thought water had to reach 100 ...
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What is the status of Mpemba effect investigations?
There is this puzzling thing that is called Mpemba effect: paradoxically, warm (35°C) water freezes faster than cold (5°C) water. As a physisist, I've been asked about it several times already. And I ...
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Why does sunset over a body of water cause a path of light stretching towards the horizon?
Have you ever notice the sunset's image in the sea? It's like long light path to the end of the horizon! I've attached a sample of this:
How can we explain this? I know that it can happen even in ...
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Patterns in laminar flow of tap water
This is a simple experiment that anyone can do at home. Open your tap so that the water maintains a laminar flow, and the cross section of flow is considerably thin. Place your finger 3-4 cm below the ...
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How to find out the maximum radius of a hole that can keep water stay in a container by water viscosity?
Assume I have a inverse cone which holds 200ml water. I am going to cut the tip of the cone to create a small hole. How to calculate the maximum radius of the hole that the water will still stay in ...
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How to show that the Coriolis effect is irrelevant for the whirl/vortex in the sink/bathtub?
There is a common myth that water flowing out from a sink should rotate in direction governed by on which hemisphere we are; this is shown false in many household experiments, but how to show it ...
user68
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Why does ice melting not change the water level in a container?
I have read the explanation for this in several textbooks, but I am struggling to understand it via Archimedes' principle. If someone can clarify with a diagram or something so I can understand or a ...
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Why is boiling water loud, then quiet? [duplicate]
Water in my electric kettle makes the most noise sixty to ninety seconds before the water comes to a full boil. I have been fooled many times by the noisy kettle, only to discover that the water was ...
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Why does blowing on someone who is wet feel colder than on someone who is dry?
The title says it all. If I'm standing in the wind and I'm wet, I feel much
colder than when I'm dry. This is true no matter how warm or cold the water.
Why is this?
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Calculation of pressure from flow rate of water
Anybody kindly help me to find how to calculate pressure in bar from flow rate. I have a pipe and from that I am transferring water at a constant flow rate of 5ml/min. At this flow rate, with a 0.5 cm ...
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Why is jumping into water from high altitude fatal?
If I jump from an airplane straight positioned upright into the ocean, why is it the same as jumping straight on the ground?
Water is a liquid as opposed to the ground, so I would expect that by ...
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Waves in water always circular
I have had a question since childhood. Why do we always get circular waves (ripples) in water even when we throw irregularly shaped object in it?
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How is the water meniscus at the edge of a capillary tube?
Suppose we have a capillary tube in which water can rise to a height of x cm.
If we dip the tube such that the height above the surface is less than x, then how will the water meniscus be at the edge ...
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Why is water clear?
Water appears transparent to visible light, yet most other objects are opaque. Why is that? Is there an explanation why water appears transparent?
Is water transparent at all wavelengths, or are ...
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Why does water pouring from a glass sometimes travel down the side of the glass?
If you have a glass of water, say, three quarters full and you pour it at an angle of say, $45^{\circ}$ with respect to the the table, the water comes out of the glass and goes directly down towards ...
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Why are snowflakes symmetrical?
The title says it all. Why are snowflakes symmetrical in shape and not a mush of ice?
Is it a property of water freezing or what? Does anyone care to explain it to me? I'm intrigued by this and ...
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Why are bubbles formed sometimes when pouring water?
Sometimes when I fill up a container with water from the tap, bubbles form on top of the water. They look a little like soapsuds, but there's no soapsuds present. I notice, sometimes this happens more ...
user110352
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Water in vacuum (or space) and temperature in space
So, water in vacuum will boil first and then freeze. I don't know how the freeze happens. As pressure lowers to zero, what happened to freezing point? (I know heat taken by vapor, and the water cool ...
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Eyes open under water
Yesterday I looked underwater with my eyes open (and no goggles) and I realized I can't see anything clearly. Everything looks very, very blurry. My guess is that the eye needs direct contact with air ...
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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 ...
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Could there be a body of water the size of a planet?
My friend and I were reading the news of the discovery of a black hole spewing huge amounts of water vapor into space, and it got us thinking: could there be a blob of liquid water in space the size ...
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Why does ice form on bridges even if the temperature is above freezing?
So with this "arctic blast" continuing, I've noticed that for my area, the temperature drops below freezing just long enough to cause freezing rain, but then the sun comes out and the temperature ...
anon
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standing waves on a cylindrical jet
as we know, there are some perturbations on a falling jet which are always present and according to their wave number and the radius of the jet, they can grow and decay over time. so, imagine a jet ...
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Why is oil a better lubricant than water?
How come mineral oil is a better lubricant than water, even though water has a lower viscosity?
When two surfaces slide over each other with a gap filled with a fluid, the different layers of the ...
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What is the reason for this pattern of noise in electric kettles?
It always seemed to me that the noise from electric kettles follows a pattern: It starts low, then increases, and decreases again before the water starts to boil.
To verify this, I performed a little ...
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Why is there more steam after a pot of water *stops* boiling?
I have a pot of vigorously boiling water on a gas stove. There's some steam, but not alot. When I turn off the gas, the boiling immediately subsides, and a huge waft of steam comes out. This is ...
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How does the freezing temperature of water vary with respect to pressure?
I know when the pressure is reduced, the boiling temperature of water is reduced as well. But how does the pressure affect the freezing point of water?
In a low-pressure environment, is water's ...
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Why doesn't rain fall down in streams (as opposed to drops)
Why is it that raindrops don't collide and 'stick together' on their descent to Earth, arriving in streams rather than separate drops?
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What determines the speed of waves in water?
While I was walking my dog this morning, I passed over a canal filled with boats, barges, and kayaks all of different masses and moving at different speeds. I noticed that all of these vessels left ...
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How fast would someone have to run to run over water?
I was thinking about Flash, the superhero, or the little boy in the Incredibles.
There is one Yahoo answer that doesn't answer a lot. Especially, I don't think surface tension would help a lot for a ...
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What is the resonant frequency of liquid water?
I learned it's not 2.45 GHz. But what is it, then? In my failure to find the real value, I'm starting to wonder: does it even make sense talking about a resonant frequency of water molecules?
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Why does ice have a lower density than water?
Can someone explain me why is ice less dense than water?
As I know, all solids are usually denser than the liquids (correct me if I am wrong).
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Thermodynamics of supercooled water
Now that it's been freezing outside for the last few days, I experimented a bit with supercooling. I've left a bottle of clean water outside for a few hours, and behold, when I shook the bottle, the ...
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Why does adding solutes to pure water lower the the specific heat?
We found that water with salt, sugar, or baking soda dissolved in it cools faster than pure water.
Water has a very high specific heat; how do these solutes lower it?
We heated a beaker (300ml) of ...
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Is there a depth at which a human body, with lungs full of air, will no longer float?
I was watching a special on divers who dove down hundreds of feet without tanks or gear. The show referred to a depth at which the diver was no longer buoyant and would actually sink, even with lungs ...
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Does a domestic microwave work by emitting an electromagnetic wave at the same frequency as a OH bond in water?
I was told once that microwaves work by exciting water molecules in food. Also that this worked because the frequency in the microwave was the same as that in the bond between Oxygen and Hydrogen in ...
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Relation between water flow and pressure
Is there any equation that states the relation between pressure and water flow.
I.e. Let's say that in 1 hour with 8mca (water collum meters) pressure I obtain 50m3. What if (giving the same ...
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Why is ice less dense than water?
The answers to this question explain that ice is less dense than water because it has a "crystal structure", but they dont explain what exactly that is and why this happens, also I saw this answer ...
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If a water molecule is neutral, how do water molecules attract one another by electric force and form water?
If a water molecule is neutral, how do water molecules attract one another by electric force and form water?
This makes no sense to me (I'm new to physics) and my textbook didn't explain this well.
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How and why does the height of water in a glass affect it's resonance? (resonant frequency)
Why does the resonance frequency of a vibrating wine glass changes with the level of water in the wine glass?
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Why does water falling slowly from a tap bend inwards?
This is something anyone could easily verify. When we open a tap slowly, water bends inwards (towards the axis) while maintaining its laminar flow. After a certain height below the opening, the flow ...
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Why is ice made from boiled water clear?
A common trick to make clear water ice is to boil pure water prior to freezing it. Why does that work and what are the white inclusions in ice that was made from unboiled tap water?
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What happens when you put water under intense pressure?
Pretend you have an indestructible tube that cannot leak, inside which is water. Imagine that in each side of the tube, you have very powerful pistons
What would happen if you compress the water ...
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Before a once-warm lake starts to freeze, must its temperature be 4°C throughout at some point?
This is a problem I just started puzzling over, and I felt this would be a good forum to check my reasoning. So here are the relevant observations followed by my question:
Water achieves its maximum ...
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Why does boiling water in the microwave make a cup of tea go weird?
When I boil water in the kettle, it makes a nice cup of tea. Sometimes I need to use a microwave because a kettle isn't available. I boil the water in the mug and it looks pretty normal, but when I ...
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Why does wet skin sunburn faster?
There is a popular belief that wet skin burns or tans faster. However, I've never heard a believable explanation of why this happens.
The best explanation I've heard is that the water droplets on the ...
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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 drop ...
user55611
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Why does water contract on melting whereas gold, lead, etc. expand on melting?
My book mentions that water contracts on melting, but the book doesn't give any reason why it does so. It is mentioned that:
$1\,\mathrm g$ of ice of volume $1.091\,\mathrm{cm}^3$ at $0^\circ\mathrm ...
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Why do crystals grow in preferred directions?
I want to know why snowflakes (and other crystals) grow symmetrically and I find the leading answer to the established question to be entirely unsatisfactory.
When water freezes, you get ice. Ice, ...
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Why does water flow out of an upside-down bottle? (Rayleigh Taylor Instability)
I am currently reading the excellent book An Indispensable Truth: How Fusion Power Can Save the Planet by Francis F. Chen and I came across this explanation.
The Rayleigh–Taylor Instability
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