Questions tagged [water]

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

Filter by
Sorted by
Tagged with
0 votes
1 answer
19 views

electrical resistance of wet wood with voltage

in recent science projects I have been studying the effect of water on electrical resistance of materials that absorb water such as wood and sponge. I am calculating resistance by reading the current ...
1 vote
0 answers
31 views

Water tower hydro generator? [closed]

$500$ gallons, $100$ feet high, at tank $10$ inch pipe, every $4$ feet a reduction of $2$ inch pipe diameter, ending in $1/4$ inch tubing to jet nozzles, each nozzle would spin an independent ...
2 votes
2 answers
67 views

Confused about how the formula for buoyancy is derived

The formula for fluid pressure of any point at depth $h$ in a fluid is $p = hρg$. Here, the formula is derived by calculating the mass of the fluid column above the point (which is equal to $Ahρ$, and ...
  • 69
2 votes
1 answer
24 views

Water equilibrium when relative humidity is high

Suppose a puddle has water and another component whose composition is known. The water in it would be in equilibrium with the water vapour following Raoult and Dalton's law (also here): $$P_T y=P^0_{...
1 vote
1 answer
36 views

Why is the weight ignored in buoyant force derivations?

why is it that the weight that the object makes is totally disregarded in these derivations of the buoyant force? Shouldn't that F up be the weight of the water in the top + the weight of the object? ...
0 votes
0 answers
14 views

Improving accuracy of water lead test [migrated]

Home water tests for lead have an accuracy of about 15 ppb. If I first do a gentle/slow boil for one hour (hot plate under a glass beaker of water) to reduce 2000 mL to 20 mL, will I then effectively ...
  • 996
4 votes
2 answers
186 views

Radius of interaction when adding an object into a boiling pool?

When you put something, like a spoon for example, into a volume of boiling water, it is well-known that the water will stop boiling, and will not start boiling again until the spoon reaches the 100 ...
  • 143
-1 votes
2 answers
60 views

Specific heat of mercury and water?

My doubt is , if mercury is denser than water , then why specific heat is lesser of mercury than water , means mercury heat faster than water , if mercury heat faster than water then again , why ...
1 vote
1 answer
25 views

How density of fluids is would affect inertia?

I was watching that movie Event Horizon and they use water as an instrument to protect passengers of a space vessel from 30G acceleration, so my question is about a similar scenario, what would happen ...
  • 11
5 votes
1 answer
530 views

Does water undergo thermolysis if a nuclear device detonates within it?

I caught a glimpse of the Wahoo nuclear test, an underwater test as part of Operation Hardtack I, and I wondered; that's a LOT of thermal energy going directly into the surrounding water, with this ...
1 vote
3 answers
75 views

Why water pressure is higher in the lower stories of a building when one can can open the faucet on the roof story and have the water free fall?

Say a building comprises 7 stories. Imagine also that the upper story has a faucet that leads to the ground (level 0) Now it is well known (alas for those on the upper stories) that water pressure is ...
0 votes
1 answer
54 views

Is tap water an ohmic conductor?

Earlier today, I asked a question regarding why I was getting weird resistance readings and based on responses which I am thankful for concluded it could possibly be the electrolysis, the fact i ...
22 votes
2 answers
5k views

Why is it harder to hear someone underwater than on air? [closed]

Because water is denser than air, sound waves travel faster and with more energy in water than air. However, we are worse at hearing in water than in air. Why is this? To clarify, I was comparing ...
  • 283
2 votes
2 answers
46 views

Can you make $\rm H_2O$ out of the air with tools anyone has? [closed]

I was just wondering if you could make $\rm H_2O$ out of the air with tools that everyone has?
0 votes
1 answer
34 views

Heat from flash frozen water

In a hypothetical situation where liquid water can flash freeze in its entirety, what would happen to the energy in it? Is it enough to feel, cook or explode something inside or around the ice? ...
  • 265
0 votes
2 answers
115 views

Cup of Tea - Luxury Item?

Some bloke was saying it costs about UK£1.80 to boil water in a kettle (for 4 people) to make a cup of tea. With all the energy crazyness going on at the moment, that is only going to get higher. Is ...
  • 111
1 vote
0 answers
28 views

How the weight of an object lighter than water changes if it is pushed and tied to bottom, going upwards and floating on the surface? [closed]

Imagine I push an object to the bottom of water with a rope (through a ring at the bottom) and attach the rope to the top of container. If I cut the rope the object will go upwards. will there be ...
0 votes
1 answer
28 views

Can you syphone water underwater by using outside water pressure?

If you have an underwater bio-sphere; is it possible, with the correct plumbing,to use the deeper outside water pressure to create a perpetual flow of water towards the shallow end where the pressure ...
2 votes
1 answer
27 views

How is underwater pressure affected by ice?

Let's say I have a bucket of freshwater exposed to an environment where ice can form (less than 0C, normal atmospheric pressure, etc.). The bucket is on the ground so ice will only form on the top and ...
  • 23
13 votes
9 answers
4k views

Why does the opposing force differ in when falling on concrete vs on water in spite of Newton's third law?

If a person jumps from the first floor of a building and lands on a concrete surface, they will suffer serious injury because of Newton's third law. If the same person jumps the same distance and ...
  • 165
1 vote
1 answer
55 views

I want to keep my chickens' water trough cool in the hot summer. Is it better to put a lead kettlebell in the water or ice of the same size? [closed]

The idea would be to put the kettle bell in the freezer at about 20F all night to cool it down and then put it into the water trough in the morning. Seems like a very dense lead kettle bell would ...
  • 439
6 votes
3 answers
894 views

How is a calorie related to the Boltzmann constant?

A (small) calorie is defined as the energy needed to increase the temperature of $1g$ of water by $1\space K$, and its value is $1\space cal = 4.184\space J$. How is this empirical value theoretically ...
  • 183
0 votes
2 answers
22 views

Is it possible to calculate some kind of friction substitute for a fast moving object sliding on water?

An object is accelerated on land, parallell to the surface of a tank of water. The object is then released onto the perfectly still water, making it slide on top of the water. Is it possible to ...
2 votes
2 answers
29 views

Does the intermolecular forces change during phase transition?

When water is heated but not yet boiling, I understand that the intermolecular attraction does not change, but the molecules vibrate more. But when water boils to gas, does the forces of attraction ...
  • 967
0 votes
2 answers
24 views

Water in house to heat and cool? [closed]

In the summer, when it reaches 27c during the day I want it to be colder, and when it reaches 15c at night I want it to be warmer. Is it possible to do some of this heating and cooling with water (...
  • 103
1 vote
6 answers
161 views

What is physically going on when I stick my finger in a glass of water and the scale tips downards implying it got heavier?

Suppose I have a scale with a glass of water on one side and a counterweight on the other side. If I stick my finger in the glass of water I observe that the water side of the scale becomes heavier ...
1 vote
3 answers
67 views

Are there any chemical reactions which result in the density of a water decreasing?

I'm not a chemist or a physicist, I'm not even college educated, so forgive me if I use the wrong terminology or do not understand the question I am asking. I understand that dissolving salt into ...
  • 13
0 votes
3 answers
78 views

Why does snow disappear without melting?

During very cold weather, snow often gradually disappear without melting.
11 votes
2 answers
719 views

How far should I spread my fingers when swimming?

One way to improve efficiency of swimming stroke is to increase area of the stroking surface - for example wear fins on hands. But what if we increase drag of the palm? If we spread our fingers then ...
  • 624
0 votes
1 answer
20 views

Calculating the leakage of water in a pressurized vessel based on initial and final pressures?

Let's say you have a piping system containing liquid water under high pressure. One section of the pipe gets isolated, and it is initially at the same pressure as when it was isolated. we can think of ...
-1 votes
1 answer
37 views

Snorkeling vs diving with a breathing cylinder

If diving with 5m snorkeling pipe our lungs would collapse due to 0.5 atm difference, right? If diving with a cylinder that has air with atmospheric pressure (the pressure our lungs can use), we can ...
1 vote
1 answer
30 views

Bernoulli's equations on a falling (not freefall) bucket of water

If a bucket of water with a tiny spout at the bottom (allowing the water to jet out) is falling (not at freefall due to a pulley system), will the air pressure above the water level in the bucket be ...
0 votes
1 answer
69 views

What if water had negative index of refraction

I was reading a book of mine that states that if water had a negative index of refraction then we'd see fish suspended in air. Why? Should not we see still it in water but far away respect to its real ...
2 votes
1 answer
74 views

Time it takes for an object to sink?

I am trying to determine how long it takes for an object to hit the bottom of the water. I've been looking at Stoke's Law, but can't quite figure out how to get to my answer. Obviously, there are a ...
1 vote
2 answers
47 views

Can hot planets host water?

Boiling point of water increases with pressure. If so, can a planet with the right atmospheric pressure contain oceans (made of water) irrespective of its temperature?
0 votes
0 answers
13 views

How to model boiling water in a pot? [duplicate]

This is a simple heat transfer problem, but I am facing some difficulties in modeling it. Let's have a tank of subcooled water at ambient pressure and let's put it above a heat source. Water ...
0 votes
1 answer
44 views

"Upward" curved trajectory from splash of bird catching fish

I captured the photo below of a great egret catching a fish. Looking at the strand of the water closest to the bird's neck, its trajectory appears to curve upward. In a purely ballistic scenario, I ...
0 votes
1 answer
75 views

How hot can steam be?

The title really says it all. How hot can steam (gaseous form of water) be before it ceases to be steam. I'm assuming that at some point the molecular bonds will give way, though I might of course be ...
  • 101
4 votes
0 answers
41 views

Why does the speed of sound in water not increase proportionately with temperature? [duplicate]

I was just wondering, as per this graph (https://www.engineeringtoolbox.com/sound-speed-water-d_598.html) why the speed of sound in water does not increase proportionately with temperature. Instead ...
0 votes
1 answer
75 views

Is there a way to calculate the number of degrees of freedom of water?

Say we have liquid water. We are given specific heat of water $C=4.2kJ(kg*K)$, a number of molecules in a mol $N_A=6*10^{23}$. The atomic weight of water is $18g/mol$, and the Boltzmann's constant is $...
0 votes
1 answer
46 views

DISPLACEMENT OF WATER [duplicate]

Floating objects displace their weight? what does this statement actually mean? Does this mean that floating objects displace the amount of water that's equal to their weight and so buoyancy is equal ...
2 votes
0 answers
18 views

Longitudinal waves - Speed of sound vs Salinity

I have read that speed of sound in water increases with salinity "Sound travels faster in the ocean because there are more molecules — specifically salt molecules — for waves to interact with, as ...
0 votes
0 answers
27 views

Best flexible material for water absorption and evaporation

I hope this is the right place to ask this as my question might more be about materials rather than any sort of theoretical physics. I want to know which flexible material can absorb the most water ...
2 votes
1 answer
143 views

Displacement of water - Archimedes' principle

Floating objects displace their weight and objects that are completely submerged in water displace their volume. So, my question is that does a floating object displace less water than an immersed ...
4 votes
2 answers
196 views

Questioning solution of lake ice melting exercise

My thermodynamics teacher solved one exercise but I'm not convinced of his solution. The exercise asks this: A lake is covered by an ice sheet of thickness $D$ given. Ice latent fusion heat $\lambda$,...
  • 180
0 votes
0 answers
12 views

Frequency and Wavelength of light in water [duplicate]

It is known that the speed of light is slower in water than in air. Does the frequency remain constant and on exiting the water, has the frequency changed?
  • 1
2 votes
1 answer
96 views

Why does rain feel like a chain reaction? [closed]

When the water droplets in clouds get too heavy to stay suspended, they fall as rain. Temperature plays a significant role in that. But why does it feel like a chain reaction when it starts to rain? ...
  • 2,085
0 votes
2 answers
71 views

For liquids where the solid doesn’t float, how does the liquid freeze?

Take for example water; when water freezes, ice floats, and given a pond or something during the winter, the pond seems to freeze from the top down. Considering a similar circumstance, let’s say we ...
  • 147
0 votes
1 answer
29 views

Calculating water pressure

We've built a waterwheel to use in a small stream and are trying to calculate it's efficiency. The Hydropower equation goes as: KiloWatts = P * Q / 600, P being pressure in bars and Q being flow in ...
  • 163
1 vote
0 answers
45 views

Building up pressure in the helix coil pump

My question is about building up pressure in a coil pump. Beginning at the scoop where the water pours into the hose and looking towards the center of the mill wheel, does the coil pump need to have ...

1
2 3 4 5
36