Force per unit area.

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2answers
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If I put a ping pong ball in a vacuum, would it pop?

If I put a ping pong ball in a vacuum, would it pop? If so, at what point would it happen? Any standard table ping pong ball is acceptable.
4
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1answer
112 views

How much pressure would be needed to contain a 1 gigaton nuclear bomb explosion within a sphere of one meter radius?

How much pressure would be needed to contain the largest human exploitable nuclear bomb within a sphere of one radius? Also would it be possible to create a magnetic field that controlled some ...
4
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3answers
901 views

Does the weight of fluid in a conical container act entirely on the base?

Scenario description Lets assume both containers have a capacity of 300 litres. One is a vertical tube as shown in pic 1 Other one is more or less a V shaped containers as shown in pic 2 Both are ...
4
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1answer
594 views

Does the pressure increase under an upturned glass?

During my children's bath time we were playing with an upturned plastic jug filled with water and making some plastic divers float up inside the jug - see image. If one of the divers swam from A to ...
4
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2answers
217 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 ...
4
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3answers
521 views

Is it easier to pump water up or down?

I'm trying to gauge the strength of aquarium air pumps, for use in a vertical hydroponic farm. A curious question arose: is it easier to pump water upwards vertically, or is it easier to pump it ...
4
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2answers
371 views

What's the classical limit of the pressure of the ultrarelativistic Bose gas

The pressure for the ultrarelativistic Bose gas is $$p~=~U/(3V) ~\propto~ (kT)^4/(hc)^3.$$ It looks to me like it diverges for $h \to 0$. Looking at the derivation, it diverges because $h$ is the ...
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3answers
500 views

How can I keep a smaller water reservoir's water level at half available when being fed from a larger reservoir? [closed]

I'm trying to create my own ultrasonic humidifier. I ordered the misting part which works great but it only functions correctly in shallow water. So I'd like to feed from a large water reservoir to a ...
4
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3answers
136 views

Why does the air pressure at the surface of the earth exactly equal the weight of the entire air column above it

Why does the air pressure at the surface of the earth (resulting from collisions of molecules on the surface of the earth which has to do with the velocity of the particles) exactly equal the weight ...
4
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3answers
286 views

How do gas molecules constantly bounce without losing energy?

From a related question (How does pressurized gas constantly push?), i asked myself this: How do gas molecules constantly bounce off each other without losing energy? If you drop a ball, it bounces a ...
4
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2answers
137 views

Could Dust Equation of State have some negative pressure?

Traditionally the cosmological equation of state of cold matter (so-called dust) is simply: $$p = 0.$$ But, in Newtonian terms, each particle is gravitationally attracting every other particle. ...
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2answers
2k views

Electrostatic Pressure Concept

There was a Question bothering me. I tried solving it But couldn't So I finally went up to my teacher asked him for help . He told me that there was a formula for Electrostatic pressure ...
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1answer
2k views

Flow of momentum is pressure

In the diagonal terms of the energy-momentum tensor, the flow of $x$-momentum in the $x$-direction is the $x$-pressure. Why the flow of momentum is pressure?
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1answer
2k views

What is the meaning of pressure of a solid?

Currently I'm taking an introductory course on thermodynamics. I've got a problem with understanding what is the meaning of pressure of a solid body. The question arose when I looked at phase diagram ...
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2answers
396 views

How to calculate the highest theoretical artificial hill?

The biggest peak in the world is Mount Everest. Imagine someone starting to make an artificial hill (like pyramide) from soil (earth). So, when starting with an 200x200 Km base area, with 45degree ...
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3answers
2k views

Why is there a 90˚ phase angle between particle velocity and sound pressure in spherical waves?

My text says that in a plane sound wave (or in the far field), particle velocity and pressure is in phase. As we move closer to the sound source (to near field and more spherical waves), the phase ...
4
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1answer
139 views

Is it possible for bubbles to exist in vacuum?

In the case of a bubble, the outside pressure is less then the inside pressure. If that is the case can bubbles exist in vacuum? I am not sure but this should be true if vacuum has zero pressure
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votes
1answer
214 views

What is the minimum pressure difference for your ears to pop?

I'm assuming the answer to this largely varies from person to person. Assuming you could instantly change the pressure around your head by amount $\Delta p$, what is the minimum $\Delta p$ for your ...
4
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2answers
134 views

How does a pierced vacuum move?

If a can of compressed air is pierced on the right, air pushes out, and the can moves to the left. If a vacuum container is pierced on the right, which way does it move? Right? Left? Not at all? ...
4
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2answers
1k views

Physics behind the flow of gas coming out of a balloon

I'm working with stratospheric balloons (latex ones) and I want to put a valve on it so it can float for a longer time. I'm trying to define which valve I should use, which demands I estimate the flow ...
4
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3answers
178 views

Effect variable cylinder radius has on airflow

Can someone shed some light on the following problem? I'm unable to get any traction on it as I know nothing about fluid dynamics (I'm a computer engineer). It's a problem I made up over a lunch ...
4
votes
1answer
204 views

Can i use coils with compressed air to make a superconductor?

What im saying is inside pipes i am going to use compressing so that that in the places with low pressure they cool the superconducotor. is this possible? Can i use this concept to make ...
4
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2answers
189 views

Initial pressure of explosion

I would like to know, if given a TNT equivalent of explosive (or its Energy) is it possible to determine what would be the initial pressure that will be the result of that explosion ? To be more ...
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1answer
430 views

Compressible fluid flow through a branched pipe junctions

Backdrop: Designing a dust extraction system (LEV) with a branched junction. What principles allow for the calculation of volume flow rate and pressure at the inlets if the volume flow rate and ...
4
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2answers
472 views

What happens to the vapor pressure when I expel the liquid phase from the vessel?

Suppose I put water in a closed vessel and heat it, so the vessel becomes pressurized above ambient pressure. Now, there should be liquid and gaseous water inside the vessel. Since it's under ...
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0answers
1k views

Inflating a balloon (expansion resistance)

I am doing a quick calculation on how to calculate the pressure needed to inflate a perfectly spherical balloon to a certain volume, however I have difficulties with the fact that the balloon (rubber) ...
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4answers
2k views

Define Pressure at A point. Why is it a Scalar?

I have a final exam tomorrow for fluid mechanics and I was just looking over the practice exam questions. They do not provide solutions. But pretty much I have to define pressure at a point and also ...
3
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5answers
398 views

Aside from carbon, what materials change structure under intense pressure?

I was thinking the other day about what sort of exotic materials one would find in the depths of a planet. I have heard theories about how an enormous diamond might be found in the centre of gas ...
3
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1answer
345 views

Pressure and Tall Buildings

Does living in tall buildings somehow exert more pressure on our bodies? I remember reading something about this once but I'm not sure if its true.
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4answers
5k views

What is the difference between air pressure and atmospheric pressure?

I know that air pressure and temperature are inversely proportional. Now I saw in a book that "Atmospheric pressure decreases as we go higher and higher." But at greater heights the temperature ...
3
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3answers
19k views

Explanation for different boiling points of water on different altitudes

I understand water boils at different temperatures depending on altitude. I am seeking to get an illustrative explanation for this, including a diagram if possible.
3
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2answers
113 views

Why doesn't water in water barometer boil?

I have read that the pressure in a water barometer at the top of the water column is around 0.5 psi and at such low pressures water should boil at around ~26°C (Room temperature). [1] [2] How ...
3
votes
1answer
875 views

Why doesn't soda fizz at high pressure?

In this video, a can of soda is opened in an underwater station at 2.5 atm. The demonstration is that shaking the soda doesn't cause it to explode like it would at normal pressures. Why does this ...
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2answers
272 views

Do I need to have an airtight container to siphon boiling water?

I'm attempting to siphon boiling water into another container for a school project. I have researched the physics of a siphon but I can't seem to make my boiling water siphon out of its initial pot. ...
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3answers
5k views

What is the relation of sound propagation to air pressure?

I am wondering, air makes sound propagate. So in a vacuum there is no sound, but what is the relation of pressure to sound volume? Is it linear? If I have a source of sound and let's say I am in a ...
3
votes
1answer
79 views

What is the maximum height for a puddle of water, assuming stp?

I wonder if anyone has figured this out. Assuming, standard temperature and pressure(273 K and 1atm), what is the maximum height of a water puddle on a flat surface? There might be some other factors ...
3
votes
1answer
447 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 ...
3
votes
1answer
714 views

What is the physics behind Roger Federer's & Rafael Nadal's iconic shots

Two Iconic players of Tennis, Roger Federer & Rafael Nadal, with two iconic shots. One with a top spin forehand & other with a slice backhand. I want to understand the physics of these two ...
3
votes
1answer
225 views

Does tapping at the side of a bottle prevent shaken soda from bubbling over?

Anecdotal evidence has it that a bottle of soda that was heavily shaken will not bubble over if tapped at the side multiple times. Yet I wonder: Has the tapping really any effect? Or could it be that ...
3
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1answer
534 views

Have negative pressures any physical meaning?

Some cubic thermodynamical equations of state predict negative pressures, have negative pressures any physical meaning? Could they be related to negative mass?
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2answers
965 views

With ideal gases, varying quantity of moles, and having a constant volume how do temperature and pressure behave?

I'm trying to build a simulation of gases so I ended-up trying to use law of ideal gases ($PV = nRT$). In my scenario: volume is constant ($V=1\rm{m}^3$); a known quantity of moles are being added ...
3
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2answers
720 views

Necessary air pressure in flexible vessel to lift a certain mass

I have the following situation in mind: A big airtight bag of arbitrary shape with a person standing on it. The bag gets inflated with air to lift the person. Assuming that the bag is much larger ...
3
votes
1answer
185 views

In a Sterling Engine, does heat from the hot side transfer to the cold side?

A Sterling Engine is a closed system. The "hot" side oscillates between higher temperature with higher pressure and lower temperature with lower pressure. Does Nature switch back and forth between ...
3
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1answer
70 views

Could fish in plastic bags filled with water float like that?

I saw this gif earlier and it bothered me how the plastic water bags with fish in it are not submerged in water like they would if we don't do anything special with the water inside and outside the ...
3
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1answer
1k views

Does water turn solid under deep ocean because of high pressure?

I know that we can make water solid with high pressure, so I think water will be solid in the deep ocean? If that is true, the depth of the ocean would be limited because water will become ice? ...
3
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1answer
1k 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 ...
3
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4answers
2k views

Dyson Air Blade as a propulsion system?

I've read from many sources that Dyson Air Multipliers are more efficient and quieter than normal fans. Now, with the proof of concept, is it possible to use its principles as a propulsion system for, ...
3
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3answers
88 views

Why is the required tire pressure inversely proportional to the volume/size of the tire?

I once noticed a tire pressure table on a farm recommended a tire pressure of around 1.0 bar (I don't remember the exact number, but it was definitely below 1.9) for the rear tire of farm tractors. ...
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1answer
57 views

How to design windy area - what variables?

When you're walking around malls or parking structures, or a building corner, you'll sometimes notice areas with consistent windiness. I was wondering what positions, angles, wind direction, ...
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4answers
3k views

Calculate water flow rate through orifice

I'm not very good with fluid physics, and need some help. Imagine the following setup with water contained in-front of a wall with an opening on the bottom: How do I calculate the water flow $Q$?. ...