Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [pressure]

Force per unit area.

0
votes
0answers
7 views

Why does Pressure exist inside a liquid?

I know this might sound like a naive question but for a while now I have been struggling with the question of why pressure acts in a liquid? Also if it is in the scope of this question could someone ...
3
votes
1answer
53 views

How does sharpening a pencil make it darker?

Why does a sharp pencil write better than a blunt one? Note that the force applied on each case is identical.
-3
votes
0answers
21 views

How to generate force with air pressure [on hold]

I am trying to figure out how to generate a substantial force for a short period of time by releasing pressure in a small high-pressure air tank. A rough estimate of the force required is 40 ...
-1
votes
0answers
13 views

Compression to Maintain Temperature

Can a liquid in a pressurized container maintain a very cold temperature merely because it is unable to expand and become a gas?
-2
votes
0answers
22 views

How do you reckon my mattress works? [on hold]

So I have one of those "sleep number" mattresses, made by Select Comfort. Good mattress. It contains two air chambers, and has a pump which can inflate or deflate these air chambers to the desired ...
-1
votes
0answers
12 views

Pressure on a Heat Exchanger in a piping system

I have a piping system that is supplied by a centrifugal pump. The system consists of pipe, 2 heat exchangers, some elevation gain and loss and ends up in an atmospheric tank. If I wanted to know ...
1
vote
0answers
68 views
+100

Is there any use of a quadratic equation of state in FLRW cosmology?

Consider standard FLRW cosmology. Usually, the relation between energy density $\rho$ and pressure $p$ of a cosmological fluid component is linear: \begin{equation}\tag{1} p = w \, \rho, \end{...
2
votes
0answers
31 views

What is the equation of state of foam, on a macroscopic scale?

Consider a large amount of soap foam (or any other substance producing foam), of mass density $\rho$ in a gravityless environment. What is the internal pressure $p$ of that foam, viewed as a fluid on ...
0
votes
1answer
19 views

Water Hammer - Max Pressure Position

When using the Joukowsky equation: P=cpu To find a pressure rise in a pipe due to water hammer. How can I find the position along the pipe from the valve closure where the pressure rise is the ...
0
votes
1answer
12 views

Does changing the volume of Hg in the container of a Torricelli barometer affect the height of Hg in the tube?

When changing the volume of mercury in the container, its mass may increase or decrease, so the gravitational force acting on the inside bottom of the container may increase or decrease, and therefore ...
-1
votes
1answer
24 views

Hole affect to pressure between 2 rooms [closed]

I have 2 rooms and pump the pressure to 20mmHg and 2mmHg and have the plate in the middle. After that I change the plate to a plate with hole 6mm diameter can I calculate the pressure after I change ...
-2
votes
1answer
19 views

Is it possible to MAKE a Jet Pump with the Specs.? [closed]

(A) Must be able to pump high density and Low viscous fluid say for ex. Mercury (B) Jet pump must be as low in weight as possible. (C) An efficiency of >80%. i.e. the ratio of Kinetic energy ...
1
vote
2answers
29 views

Are forces of gases intensive or extensive?

What am I wrong at in here: I read that pressure is an intensive property. According to this and to $P=\frac{nRT}{V}$, can this be true: $(1)$: When $V$ is constant, increasing $n$ won't increase $P$,...
0
votes
1answer
24 views

Calculate change of pressure in a football due to insertion of a solid ball [closed]

Let's say I have a football of radius r1 inflated to pressure p1 and insert a solid metal ball of radius r2 (without losing any air), to give a new pressure of p2. Is there a formula I can use that ...
0
votes
2answers
45 views

Pressure being isotropic

We say pressure is isotropic. At any point in a fluid pressure acts equally in all directions, but pressure is perpendicular force per unit area so how can pressure be there in all directions as ...
0
votes
1answer
32 views

can generation of pressure create light?

If pressure is applied on a body , can mechanical stress produce light? , as electrons are produced in piezoelectricty. if yes , please answer or recommend any book/website/paper. Thank you
0
votes
1answer
55 views

Why did the liquid disappear from some unopened aluminum cans? My experience (read below) has not been answered [duplicate]

I’m posting my question because I read this original post. The post was from 2016, so I’m reposting in hopes that someone can answer. Here’s the original post: (Also, do not flag as duplicate. If you ...
0
votes
0answers
24 views

Hydrostatic pressure vs static pressure in a fluid

hydrostatic pressure is the scalar and isotropic pressure exerted by a fluid at rest at a certain point inside the fluid itself on the neighboring fluid parcels or on on an elementary differential ...
0
votes
0answers
24 views

Water vapor pressure in oxygen bubble

Suppose we have a source of O$_2$ bubble formation in water at specific nucleation sites, how can we estimate the water vapor pressure inside the O$_2$ bubbles? I know that: (1): $p_\mathrm{O_2}+p_\...
0
votes
1answer
36 views

Hydrostatic pressure: clarifications

Hydrostatic pressure is due to the weight of liquid. Do liquid molecules exert pressure on their neighbours molecules or only in objects that are in contact with them?
-1
votes
1answer
31 views

Constant pressure

When we refer to constant pressure like in Charles law what is this pressure? The pressure of the gas or the pressure that the container (the piston maybe) exert on the gas? Also does atmospheric ...
0
votes
0answers
22 views

Stable bubbles in a vacuum

I want to make space bubbles that hold some gaseous stuff - at very low pressure - for a long time and through nothing but surface tension. I can't use soap water as the water will evaporate quickly. ...
0
votes
1answer
31 views

At what pressure do semiconductors break down? [closed]

So let's say you were going to send some electronics to the bottom of the ocean, 3-5km down. This would be about $5km*1000kg=5Mkgf/m^{2}$. So at what pressure do circuit boards, transistors, etc stop ...
-2
votes
1answer
38 views

When a carbonated drink is opened, why does the liquid tend to flow out?

In other words, why does the coke flow out of it's bottle/can. Isnt the air trapped inside the container, so the air must flow out? What pushes the liquid to go outside the container? For example, we ...
3
votes
1answer
42 views

Why does the pressure change on uniformly mixing two liquids?

The two cylinders are connected the upper cylinder has a cross-section of A and the lower one has a cross-section of 2A (I've taken the cross-sections to be A and 2A as they are easier to work with ...
0
votes
1answer
46 views

Relative humidity, definition and its dependence on state variables

Relative humidity ($RH$) is defined by the following equation: $$ RH = \frac{p_{vap}}{p_{sat}} $$ Where $p_{vap}$ is the vapour pressure and $p_{sat}$ is the saturation vapour pressure. VAPOUR ...
0
votes
1answer
15 views

Why isn't the volume of the individual gas particles relevant to the total pressure in Dalton's Law of Partial Pressures?

I was reading about Dalton's Law of Partial Pressures in a textbook and the proposition is that under ideal conditions, the relevant factors are the pressures of the individual gases and their number ...
0
votes
1answer
32 views

PV diagram of pure substance

Why does the specific volume of saturated solid state of water decreases with increasing pressure and the specific volume of saturated liquid wrt vaporisation increases with pressure? Can anyone ...
0
votes
1answer
23 views

What would be the total pressure in this container in accordance to the Ideal Gas Law?

If I had an apparatus such as the one below: where each of the four blue lines represents a valve, and then I was to open the three lower valves such that the pipes connecting the three containers ...
1
vote
0answers
60 views

Demonstration of magnetic field lines “tension” and “pressure” using the Maxwell stress tensor

I would like to show that the magnetic fields lines are under "tension" along the lines and exert "pressure" perpendicularly to the lines, using the Maxwell tensor only. I have a sign ambiguity. In ...
14
votes
6answers
3k views

How is pressure an intensive property?

I've seen this question asked before but I can't find an answer to the specific point I'm troubled with. From the kinetic theory of gases, pressure results from molecules colliding with the walls of a ...
1
vote
0answers
36 views

Why are diamonds formed under high pressure? (use entropy)

My book asks how can diamond ever be more stable than graphite, when it has less entropy. I have to explain how at high pressures the conversion of graphite to diamond can increase the total entropy ...
0
votes
0answers
20 views

Do the height of the water columns decrease when we push pistons with constant speeds in this venturi pipe?

Let say when the pistons are kept stationary the height of the water columns are h. And we start exerting extra force on the left piston in figure, and the pistons are moving with constant speeds. ...
2
votes
0answers
50 views

Proof that pressure rises in a fixed control volume

I am looking for a proof using Bernoulli's equation that that for $Q=(Area)(Velocity)$, $Q_{in}>Q_{out} \Rightarrow P_{inside}>P_{outside}$. I read that for a computer, if the case fans blow a ...
36
votes
8answers
6k views

Can a battleship float in a tiny amount of water? [duplicate]

Given a battleship, suppose we construct a tub with exactly the same shape as the hull of the battleship, but 3 cm larger. We fill the tub with just enough water to equal the volume of space between ...
0
votes
2answers
33 views

What happens to the pressure time graph when two musical instruments play at the same time?

I'm learning acoustics for the first time and I'm having trouble picturing what the pressure time graph would look like when two instruments play together. https://newt.phys.unsw.edu.au/music/flute/...
1
vote
1answer
21 views

Increase Air Speed at outlet

I have a set up that inflates a rubber jacket in order release the metallic rings from underneath it. I am currently having issues with not having enough pressure (force) at the outlet to inflate the ...
0
votes
1answer
67 views

Could a sufficiently massive Dyson Sphere under very specific conditions depend solely on electron degeneracy pressure for structural integrity?

Stuck in an argument. I claim this is theoretically possible: Provided you could build a type 1 Dyson Sphere, made from a supposed material that rivals the structural integrity of a white dwarf, i.e. ...
4
votes
1answer
102 views

How is pressure calculated in the early universe?

I'm trying to calculate the sound horizon from the start of time to decoupling. To do this I need to know the speed of sound and how it changes as the universe grows. The speed of sound in a fluid ...
0
votes
1answer
41 views

Limitations of converting pressure into kinetic energy

Bernoulli's principle states that an increase in the kinetic energy of a fluid occurs simultaneously with a decrease in pressure for isentropic processes. What then limits us from converting all of ...
3
votes
0answers
30 views

Temperature-pressure plot for superconducting records?

Eremets et al. (arXiv:1812.01561) and Hemley et al. (arXiv1808.07695) have reported new high-temperature record for superconductivity, as covered by MIT Tech Review and Physics Today. Not ...
1
vote
2answers
41 views

Microscopic idea of sudden extreme pressure difference

I'm having some issues understanding what's happening microscopic when there's sudden changes in the pressure. The microscopic idea, is that particles randomly bounces around each other. It's even ...
-1
votes
0answers
25 views

Pressure in fluid [duplicate]

Why do liquids exert pressure? Is it because of their mass only or because of their random collision with each other and the walls of the container also. The formula P=hdg talks of the pressure due to ...
0
votes
1answer
32 views

Does increasing the stroke of a pneumatic cylinder create a need for a thicker wall?

So say you have a pneumatic cylinder (ram) with a certain length and wall thickness. The ram is pressurized to the same pressure each time (1000psi) Force is equal to pressure x area. So as the ...
-1
votes
1answer
97 views

How can the Friedman Equation produce negative pressure or density?

As I understand it, the Friendman Equation provides the driving mechanism for Inflation.$$\frac{\ddot a}{a}=-\frac{4\pi G}{3}\left(\rho+\frac{3p}{c^2}\right)$$If $\rho$ or p is negative enough, you ...
0
votes
1answer
29 views

Hollow cylinder pressure tolerance [closed]

I have a physics\material science problem. We have a hollow cylinder with length L, inner diameter d and outer D made of a material with known mechanical properties(whatever constants are needed). ...
0
votes
1answer
30 views

Why isn't right piston moving down even if a heavy car is resting on it?

I have understood the concept that pressure at same height should be equal but what about the weight of car that will also push the piston and pressure would change and left piston should go up, some ...
1
vote
0answers
21 views

Effect of total pressure on the component condensation in a gas mixture

Suppose we take two gases in a vessel with a movable piston. We compress the mixture until first drop of condensate appears. Suppose temperature remains constant during compression. Therefore when you ...
0
votes
1answer
54 views

Simple experiment proving air pressure is stronger than water pressure at sea level [closed]

I conducted a simple experiment I: pour a little of water into a cup, put a card on top & turn all upside down. The card does not fall $\Rightarrow$ $$P_i + P_w < P_o\tag{1}$$ $P_i$ : air ...
0
votes
3answers
48 views

How does a gas spring work?

I read Wikipedia and do not understand the following. If you create pressure on the gas (or any spring) it gives pressure against. Why is the gas spring holding mass when pulled out, and while ...