Force per unit area.

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0
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4answers
101 views

Find pressure of liquids without making contact with it

Is there any way to find the pressure of a liquid inside a closed container without making contact with it? You can make any assumptions, like transparent container or anything, only rule, the ...
1
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2answers
44 views

water pressure in the oceans or great lakes

Is there a way to create energy from water depth pressure? Convert the pressure to any type of energy? Does there need to be movement? Can someone comment on this process? Thanks
-1
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1answer
128 views

Looking for the name of a physical phenomenon in fluids' mechanics

I have not even an idea about how I would search for that on Google, that is why I'm trying my chance here. As electrical engineer I have no clue about fluid mechanics. We all now that when water is ...
0
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1answer
39 views

Change in volume of air held at the top of a tube with upper end closed and holding some liquid [closed]

Consider a tube both end open.dip one end in a container with water..close the top with your thumb..(make sure some air remains between your thumb and the liquid in the tube)..now take the tube out of ...
5
votes
2answers
329 views

How come a whistling kettle starts whistling only when water boils, and not long before - due to hot air escaping under pressure?

A whistling kettle will start to whistle when the water boils and turns into a jet of steam which then exits the small aperture in the spout. But why doesn't this happen much earlier - when the air ...
2
votes
1answer
315 views

What is the pressure at the top of a sealed tube being drawn out of water?

Is the atmospheric pressure in a closed container the same as that of the surroundings (1 bar at sea level)? Consider a tube with both ends open with one end dipped into water (like a pipette in ...
6
votes
6answers
38k views

What is the difference between stress and pressure?

What is the difference between stress and pressure? Are there any intuitive examples that explain the difference between the two? How about an example of when pressure and stress are not equal?
1
vote
1answer
59 views

Do gases have a general upper limit of density?

Is there some limit for the density of gases, at which no change in condition could make it more dense without making it fluid, or solid - or something 'in between'?
1
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2answers
3k views

Why doesn't our body gets crushed due to the atmospheric pressure? [duplicate]

The atmospheric pressure is 101325 Pa,which is good enough to get our bones crushed.But why aren't we crushed due to it?
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1answer
110 views

Pressure at the front and back of a fan

I have a fan which is inside a duct. When the fan is off, the pressure at the front and back of the blade remains the same. Now when it is running, the velocity of the air below will be more because ...
0
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2answers
350 views

Can a submerged capsized vessel be turned into a sort of diving bell and propelled forward like a submarine?

I am writing a story set in the 17th century and have read accounts of such early submarines, however, not much detail is available. If some kid of weights/plummets are attached to the sides of the ...
-1
votes
2answers
21k views

How to calculate gauge pressure at water depth? [closed]

I am creating a program that will calculate danger at water depths for sensitive equipment and maybe humans. How do I calculate the gauge pressure at a depth $D$. Lets say $D = 5000$ meters. My ...
0
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1answer
109 views

Viability of Dysons bladeless fans? [closed]

Do Dyson's bladeless fans produce enough air pressure to cool say an air conditioning unit and do they produce a vortex pressure like a bladed fan?
0
votes
2answers
122 views

requirements for hydrogen fusion

What are the requirements for hydrogen atoms to go through fusion? Is it a ratio of heat to pressure or are there specific heat and pressure values that must be met (per atom or per mole?) Are there ...
5
votes
3answers
395 views

Home experiment question

I want to make a home experiment where I roughly explain the phenomenon of water remaining in a straw if you close one end of the straw. So I'm thinking that the weight of the water is pulling it ...
1
vote
0answers
22 views

Radiation pressure at high temperature

I am reading a book on the history of the hydrogen bomb. The author describes the Teller-Ulam design and explains that the liquid deuterium charge was compressed by the radiation pressure generated by ...
0
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2answers
7k views

Why do particles in high pressure air always flow to lower pressure?

The title really says it all: Why is this case? A "Feynman type" answer would be really appreciated as I'm more of a layman that a physicist.
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vote
3answers
128 views

Why doesn't water start to boil in soils?

Consider the following two scenarios: I take a vessel filled with some water and evacuate the air, the water will (or rather can) start to boil; if the pressure in the vessel is << atmospheric ...
1
vote
1answer
108 views

Gases at different pressures reaching uniform pressure

First of all, sorry if my question is dumb, I have very little understanding of physics. Also, English is not my native language. If two gases, initially with different pressures, are mixed in a ...
1
vote
2answers
344 views

Why does a microphone membrane only measure pressure and not particle velocity?

Microphones (e.g. condenser microphone) are assumed to have a voltage output proportional to the sound pressure at the diaphragm. If the operating principle is that the voltage output is proportional ...
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 ...
0
votes
0answers
33 views

How does atmospheric pressure work? [duplicate]

I heard that yesterday the atmospheric pressure at my location was exceptionally higher than normal and that explained why I had such a terrible headache all day. But what remained unclear was... How ...
1
vote
2answers
230 views

Can an extremely small force lift a mountain in a hydraulic system? If not, then why not?

As you see in the picture, a car can be lifted with a small force F1. Here it is shown that 'F1 . A1 = F2 . A2'. What will happen if A1 is of the size of a pin's cross-sectional area. Can a child ...
1
vote
0answers
39 views

Electrical resistance of a metallic conductor in a gas

A long time ago I learned that the electrical resistance of a metallic conductor, when surrounded by a gas, varies with the pressure of said gas. • What is the name (if any) of the law involved? • ...
47
votes
5answers
13k views

Why does a candle blow out when we blow on it? Our breath is 16% oxygen and only 4% CO2

Don't say that a layer of carbon dioxide covers the flame, because our breath has more oxygen than carbon dioxide. Also, our breath does not cool the flame as it is itself warm. So what is happening ...
3
votes
2answers
166 views

Why don't we include $\rho g h$ in a hydraulic jack below?

Consider a hydraulic jack with massless pistons as follows. The famous equation for this system is $$ \frac{F_1}{A_1}=\frac{F_2}{A_2} $$ My question is why isn't the equation as follows? $$ ...
0
votes
1answer
134 views

Airfoil theory — Why does air travel faster above? [duplicate]

I do not understand, why the air above the airfoil travels faster than the air below it? The air above has to travel faster than the air below so that both streams meet simultaneously at the ...
2
votes
1answer
1k views

Where is the atmospheric pressure equal to zero?

Consider the following question. My calculation is as follows. \begin{align*} P_C = P_A + \rho g h\\ P_A = P_C - \rho g h \end{align*} Because $P_C=P_0=\rho g h$ then $P_A=0$. Is it correct that ...
2
votes
3answers
535 views

How much energy needed to push a volume of water?

I am trying to solve a situation, where I'd like to know how much energy would be needed to push a mass of water out of a container. Here's an image to help understand: The water tank has a height ...
1
vote
1answer
114 views

Inward Pressure of Gravity

We are looking at White Dwarfs in Quantum and specifically how they are stabilized between gravitation pressure inwards balanced by the Fermi pressure due to electrons. To start the problem off ...
0
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2answers
1k views

Difference between pressure and stress tensor

What is the difference between hydrostatic pressure and stress tensor?
0
votes
1answer
3k views

Compressed air in a volume: Can I determine its temperature?

Using a compressor, I augment the pressure in a volume (using atmospheric air). I only measure the pressure inside. I now that the density will increase however, the temperature decreases. Can any one ...
2
votes
3answers
111 views

How does pressure factor into mechanics?

We just started learning about pressure in our school, and i am a bit confused. I tried to google extensively, but i didn't really find much. In mechanics, so far in our school we've been taught ...
1
vote
1answer
139 views

How to caculate the pressure of a fluid when there is no gravity

Well for example we put a ball filled with water, with a density of $1\cdot 10^3 kg/m^3$, in space. How to calculate the pressure the water is exposed to?
3
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1answer
2k views

Question on the hydrostatic paradox

The hydrostatic paradox, states that the height of the water in any container is independent of the shape of the container. This does make sense since it is only the height of the fluid ...
7
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2answers
141 views

Why does a tail of a balloon poodle not collapse?

I was just wondering. How can it not collapse? There is pressure in the tail top and in tail itself. How can that little "bridge" (with that I mean the part that in not inflated, see image 2) and tail ...
0
votes
1answer
102 views

How the tube of a tire get puncture?

How the tube of a tire(cycle) get puncture? I mean, the inner tube is protected by an outer tube, so how is it possible to make a hole in the inner tube? And in general the puncture hole is very ...
1
vote
1answer
155 views

What does the absence of hydrodynamic entrance effects do to the momentum conservation Equation?

I am trying to do a homework problem where we re-write the mass, momentum and energy conservation formulas for downward flow in a vertical pipe and it says "where all hydrodynamic entrance effects ...
1
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0answers
184 views

Maximum pressure of a rubber balloon

I've had a question about this topic previously, but the material was inelastic. Forces in a balloon popping? What happens when a material is non-hookian? Say rubber, I've found this pdf on the ...
1
vote
1answer
150 views

gas pressure outside nozzle in vacuum

I'm currently trying to figure out the following in the simplest possible way: Say we have a nozzle in a vacuum environment. A gas of a certain pressure is emitted through the nozzle, which has a ...
0
votes
1answer
131 views

Conclusions From a Junior School Science Experiment

If you stick a tissue to the bottom of a glass and immerse this glass fully (upside down) into a tumbler of water, then this tissue remains dry. Why is this so? / What conclusion would you draw from ...
11
votes
5answers
7k views

Why does my door shut faster when the window is open?

I've noticed that if I shut my door when the window is open in a room, the door will tend to shut faster. If I shut the door when the window is closed with a normal force it will not fully close as if ...
0
votes
2answers
137 views

Simulate free fall in a rotating torus?

Say I have a rotating torus filled with air at 1 atmospheric pressure at sufficient speed (and inclined along the direction of the force of gravity with respect to Earth). If the rotation speed were ...
0
votes
1answer
149 views

What is responsible for cutting an apple: pressure or force?

To cut an apple, do I need more pressure or more force? When we want to destroy the intermolecular bonds, don't we need more force ?
0
votes
1answer
858 views

Accelerated liquid in a U-tube

Consider a U-tube containing some liquid. The two ends of the tube are connected to closed volumes of air with different initial pressures, such that there is some difference in the liquid levels ...
0
votes
3answers
105 views

How does pressurized gas constantly push?

If a gas, such as hydrogen, is pressurized into an air tight container, a force in terms of pascals (or whatever unit you want to use) is exerted, correct? That is what pushes against every surface ...
2
votes
1answer
117 views

Why is pressure always non directional? [duplicate]

While hammering a nail (before it is in the wall) it is pretty evident that the tip of the nail is going to be applying a force directed along th axis of the nail, then why is it said that pressure is ...
0
votes
1answer
181 views

How to calculate fluid(oil / hydrocarbon) loss under pressure

I'm trying to calculate the amount of fluid that would flow through an area dependant on the amount of pressure that there is. I'd also like to know the rate at which it would flow. Essentially I ...
3
votes
1answer
574 views

How far do air particles move when a sound wave passes through them?

How far do air particles move when a sound wave passes through them? I know that they don't actually travel, the question is how far do they oscillate or what is the physical amplitude of the ...
0
votes
1answer
4k views

What is the basic difference between absolute pressure and gauge pressure? [duplicate]

What is the basic difference between absolute pressure and gauge pressure? I have a great confusion regarding these two pressures. Please someone explain it to me