Force per unit area.

learn more… | top users | synonyms

1
vote
1answer
20 views

Coherence of pressure and mass flow in a pipe [closed]

What is the coherence of pressure and mass-flow in a horizontal pipe? Let's assume I have just one pipe with pressure = 1.5 bar at the input and through pressure-losses 1.2bar at the output. Is there ...
1
vote
1answer
36 views

Do liquids creep from cold to hot like gases?

Consider the U-tube water experiment below with the left red block at 10C and the right red block at 90C. I think the right level will become about 3% higher than the left level simply because hotter ...
1
vote
2answers
44 views

Volume integral of pressure interpretation

If you have a fluid with with pressure field $p$ what is the physical significance of the the volume integral of the pressure $\int_V p dV$?
1
vote
1answer
68 views

Why did my bag of chips expanded in airplane and didn't get back to normal after landing?

I bought a usual bag of chips and took the plane. In the air, it seemed that it was pretty much expanded, as if it was going to explode. I thought to myself : ok that's normal, the pressure in the ...
1
vote
1answer
34 views

Density profile in the atmosphere, which equations to use…? [closed]

I came across the following density profile in the atmosphere: ...
1
vote
1answer
38 views

How much carbon dioxide do we actually ingest from a can of coke?

On this most trustworthy page it states that a 355 mL can of coke contains on average about 2.2 grams of carbon dioxide. As far as I know, this carbon dioxide can exist in solution as carbonic acid, ...
1
vote
1answer
57 views

Putting an open can of soda into a loose plastic bag to preserve its fizz?

A friend insists that, to preserve the fizz in an open can of soda, you just put it in the refrigerator inside an unsealed plastic bag. The theory is not that the bag preserves the pressure in the ...
1
vote
1answer
89 views

Find the separation distance for a line of oil being squashed between two flat plates [closed]

I was wondering if someone could give me some help on how to start this problem, I'm really struggling to get my head around it. A long line of oil is being squashed between two flat plates of length ...
1
vote
1answer
1k views

water fountain with a pipette

if you get some hot water in a pipette an put the pick of it on the top the water will jump out f pipette and make a fountain.I wondered if any one could tell me what is the reason?
1
vote
1answer
85 views

Can you blow bubbles on top of Mount Everest?

Can you blow bubbles on top of Mount Everest? How would they be different in low temperatures and pressures?
1
vote
1answer
617 views

How do I keep the temperature constant in a Boyle's Law experiment?

I'm trying to get a head start on our lab experiment next week about Boyle's Law. The set-up is we have an air chamber can immersed in a pot of boiling water (which is kept boiling over an electric ...
1
vote
1answer
224 views

How do I calculate the maximum pressure a container can withhold?

Say I have a spherical container with a certain gas inside, heated to a very high temperature, and thus a very high pressure. The gas will exert a force radially outwards onto the container, and at ...
1
vote
1answer
34 views

sound waves and atmospheric pressure

Is it possible to use sound waves (ultrasound/infrasound or whatever) in order to make some space have lower atmospheric pressure? Or maybe another way to achieve this? I was thinking that maybe sound ...
1
vote
1answer
256 views

Determine fan sound (dB) based on its rotational speed (RPM)

I am trying to find the sound amplitude or level produced by a fan, knowing its RPM. Is there a simple formula for it? What other parameters does it depend on? Assume I have all the fan properties, ...
1
vote
3answers
181 views

Calculate pressure with the ideal gas law or $\rho gh$?

In a container the pressure on the walls due to a gas can be calculated using the ideal gas law $\bigl(pV=NRT\bigr)$. However, for a column of water, or the pressure at earth's surface due to a ...
1
vote
3answers
327 views

Direction of pressure forces on a control volume (surface)

According to http://www.mne.psu.edu/cimbala/Learning/Fluid/Pressure/pressure_basics.htm, "Pressure always acts inward normal to any surface (even imaginary surfaces as in a control volume).". ...
1
vote
2answers
128 views

Can pressure be negative? [duplicate]

From Wiki and from physics fundamentals lections I received info that pressure is scalar value. But in definition you have relation between projections of two vector values to normal axe-force and ...
1
vote
2answers
82 views

Heating suprecritical water in a closed water tank

How does the pressure of water in a closed tank evolve in the following setting: - closed tank of 2 liters (filled up with water) - water initially at 25°C and pressurized to 3 bars The water is now ...
1
vote
1answer
987 views

How does the bulk modulus of air change with rising pressure?

I can't seem to find the answer to what should be a trivial question: I have a rigid air-tight container of fixed volume and I am pumping air inside. The pressure is increasing (very slowly) from ...
1
vote
1answer
64 views

Static pressure in ducts and its dependency on speed flow and density

I know that depending on the duct circuit (bends, complex geometries...etc), the static pressure will be defined. If we assume air is flowing in the circuit with varying speed and/or varying density. ...
1
vote
1answer
55 views

Deriving pressure from a given partition function

If the partition function for some system is given as $e^{\text{$\alpha $T}^3V}$; please note note that $\alpha$ is a constant. I have computed $$\left[\frac{\text{$\delta $Z}}{\text{$\delta ...
1
vote
1answer
105 views

Determining the components of the force on a curved surface due to pressure

I have a cross section of a half-tube with a pressure gradient across it causing a force outwards. I am attempting to extract the vertical component (in relation to diagram) of the force on this ...
1
vote
1answer
180 views

Difference between hydrostatic and uniaxial pressure

I'm confused with these two terminologies. Does 'hydrostatic' means every direction while 'uniaxial' means one direction? What're they usually used for?
1
vote
2answers
120 views

Microscopic definition of dynamic pressure of fluids

So we have a moving fluid and we know from Bernouli's equation that there is a term called dynamic pressure(not to be confused with the hydrostatic pressure of the fluid). So,what exactly is it and ...
1
vote
1answer
145 views

why doesn't liquid metal vaporize in a vacuum?

I am wondering why molten metal in a vacuum of electron beam and machines never turns to gas like liquid water does when exposed to a vacuum.
1
vote
2answers
144 views

Pressure-Velocity relation at a point in a flow

How can we relate pressure and velocity at the same point in a fluid flow? Why does pressure decrease with increase in velocity?
1
vote
1answer
589 views

What is the differential equation for pressure in a container with an orifice?

I've seen similar problems all over physics.SE and other sites. Most of the time it is about non-compressible fluids, or not about the differential equations. The physical system of interest is ...
1
vote
1answer
97 views

Air Presure and Air Velocity from speaker

How do I determine/calculate the air pressure emitted from a speaker ? And how to determine the velocity of air from the sound air pressure ?
1
vote
1answer
167 views

Pressure Question

I have a question that relates to an arrangement of natural gas pipelines but for simplicity I will be describing a less complex problem. Imagine that I have two large pressure vessels connected by a ...
1
vote
1answer
67 views

Boiling is not well described? [duplicate]

It is said that boiling occurs only when the vapour pressure becomes equal to the pressure surrounding the vapour (say atmospheric pressure). Why does it take place only satisfying these conditions ...
1
vote
1answer
7k views

How does a plunger (toilet plunger) work?

I don't quite understand the physic involved in operating a plunger. I thought that using a plunger on a clogged sink, for example, would create a difference in pressure inside the tube so that, ...
1
vote
1answer
131 views

Pressure and variation in pressure due to depth

In my class, we were shown the following problem: Using the equation $P_1$ = $P_0$ + $\displaystyle\rho$gh, where $P_1$ is the pressure at Superman's mouth and $P_0$ is the pressure at the surface ...
1
vote
1answer
89 views

Is there an equilibrium for water and air in a tank?

I'll try my best to explain my question with examples because I don't have much knowledge on the theory. So say that I had a block of water in air, a cube of water, that is dropping. If the cube ...
1
vote
1answer
4k views

Work Done in a Thermodynamic System (Cylinder with Piston) [closed]

Heated Piston A cylinder of cross-sectional area 0.0314m^2, filled with argon (a monatomic ideal gas), is sealed with a piston of mass M=25kg that is free to move up and down. The piston is ...
1
vote
1answer
536 views

Do different density objects in liquids affect net weight [duplicate]

I would test this but I have no tools to test it with. If I have a beaker of water and weigh it on a measure. Then I stick my fingers in the water (it doesn't over flow) does the weight change or ...
1
vote
1answer
310 views

Pressure and Buoyancy [closed]

It is well known that you can trap water in a drinking straw by placing the tip of your finger over the top while the straw is in the water, and then lifting it out. The inner diameter of the straw is ...
1
vote
1answer
156 views

How to measure the pressure on the walls of a potential box by a particle inside?

Consider a quantum particle inside a 3D potential box. One can compute the pressure that it exerts on the walls, it's OK. But what puzzles me is how do we actually measure such a pressure? If we take ...
1
vote
1answer
45 views

Variable area manometer duct

How does one measure the pressure at the end of the manometer tube when the manometer tube itself is having a variable area?
1
vote
1answer
159 views

Simple expression for transitional pressure force

Consider a simple, circular orifice with an upstream, high gas pressure and downstream, normal atmospheric pressure. Consider also a flat circular plate that can be positioned anywhere along the ...
1
vote
1answer
210 views

Gauge pressure clarification

Is gauge pressure always zero-referenced against ambient air pressure? Or is it referenced against the sum of all pressures acting on a fluid, which usually just happens to be ambient air pressure? ...
1
vote
2answers
2k views

Pressure vs Volume Calculation for air [closed]

I have 1 litre of air in a sealed container at atmosphere pressure (approx 15 psi absolute). I want to reduce pressure in the container by 1 psi ( 14 psi absolute or -1 psig). If I understand ...
1
vote
1answer
28 views

Decompression speed (rate)

I've heard that decompression speed or rate in which the gas will leave the greater pressured container is equal to the speed of sound. For example, if the spacecraft gets damaged the air cannot exit ...
1
vote
1answer
46 views

maintaining atmosperic pressure on mars

how would mankind be able to maintain an earth like atmospheric pressure on mars since mars only has 1/3rd the mass? I am not, nor have i ever attended college, but am very curious.
1
vote
2answers
7k 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?
1
vote
2answers
440 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 ...
1
vote
1answer
146 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 ...
1
vote
1answer
191 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?
1
vote
1answer
211 views

Energy conservation at a the end of a hose pipe?

I am trying to figure out the energy balance at the end of a hose pipe with water pouring out. Applying Bernoulli's equation inside the pipe we have three energy terms: Kinetic energy, "pressure" ...
1
vote
4answers
873 views

Pressure in fluid mechanics of incompressible liquid

Most liquids can be approximated to be incompressible, since the Mach-number is much smaller than 1. That means that the density variations are negligible and from the relation between pressure p and ...
1
vote
1answer
413 views

Is temperature-induced change in the volume of balloons dependent on gas?

Which balloon will have higher relative change in volume, helium balloon immersed in liquid nitrogen or air balloon immersed in liquid nitrogen? Since volume is directly proportional to temperature ...