Pressure Definition and 999 Threads

Hey people, I have a pressure vessel pressurized to say 20MPa at 33C, of which I'm working with a gas (scCO2 to be exact) which will then be released into the atmosphere (standard pressure and temperature) through a release valve; I'm wondering how long it will take for the pressure to reach...

Homework Statement An airgun shoots a ball made from lead, through air of high pressure that pushes the ballforward like a piston. Because this happens very quickly, Q = 0 and the process is adiabatic. The initial volume of the air is Vi = 12.0 cm3 = 12.0 * 10-6 m3, which behaves as an ideal...

Homework Statement on a flat desk is an aquarium with a volume of 640 cm3 ,t's not full of water. The pressure to the bottom of the aquarium is 3 times bigger than to one side of it, how much water is in the tank? Homework Equations is the pressure, is the normal force, is the area of...

This seems simple, but I have some confusion. I'm trying to refine a numerical simulation to get away from my isothermal assumption, to account instead for isentropic temperature and pressure changes in pressure tank with an orifice. Given an insulating air tank of volume ##V##, containing air...

Hi guys! I have question regarding vacuum and underwater pressure if anyone here could help me out with it. I'm not really a physics person (my math skills suck too much, lol), but I do find it very interesting. I recently bought some breathable stockingfoot fly fishing waders and whenever I...

Something that routinely comes up as a problem at work is when we size flow projects for piping systems. We calculate pressure drop across a length of fixed diameter for compressible gasses, but we do not calculate pressure changes through an expansion or contraction with gas (for example...

Considering the angular momentum of a collapsing star preventing it from resulting in a black hole by degeneracy pressure, are there ekpyrotic universe models that include angular momentum and degeneracy pressure as key factors of cosmic inflation?

is there any way to derive p=rho/3 from 4 vector or stress-energy tensor?

Homework Statement One mole of an ideal gas is warmed slowly, so that the pressure and volume go from (Pi, Vi) to (3Pi, 3Vi), in such a way that the pressure is analogous to the volume. a) What's the Work (W)? b) What is the correlation between the temperature and the volume during that...

Hi Please have a look on the attachment. Suppose that a 0.1 kg rubber ball having velocity of 60 m/s is moving between two walls A and B, and the distance between the walls is 1 m. It is having elastic collisions with the walls. Let's focus on what is happening at wall B. The ball is moving...

Homework Statement In a container we have a gas, at P = 11.0 atm & T = 20.0 C. We remove 2/3rds of the gas and increase the temperature to T = 75.0 C.What's the pressure of the gas that remains? Homework Equations PV = nRT The Attempt at a Solution Normally this would be a regular "put...

Hi, The air pressure at the surface is about 1,00,000 N/m2. It means that on average, a virtual column of air one square meter [m2] in cross-section, measured from sea level to the top of the Earth's atmosphere, has a mass of about 10,000 kilograms and weight of about 1,00,000 Newtons. That...

I'd like to explore water pressure by having students build water towers out of both 2-liter bottles and thinner 1 liter bottles. 1. Assuming they build towers of the same height and fill them with the same type of water, we should see the same water pressure for identical heights within the...

I am currently new in this forum and just a senior high graduate, so pardon me if I have some errors in writing this questions. I have a cylindrical pressure chamber with approximately 80 cm in diameter and the length of 1.5 m and metal wall 1 cm in thickness. I know most pressure chamber have...

A container of water is sitting on a scale. I dip my finger into the water without touching the sides or bottom of the container. Is it true that the force exerted on the scale by the container will decrease because the finger creates a downward force?

A body is reentering the Earth's atmosphere at a Mach number of 20. In front of the body is a shock wave. Opposite the nose of the body, the shock can be seen to be normal to the flow direction. Determine the stagnation pressure and temperature to which the nose is subjected. Assume that the air...

I read in some scripts that equilibrium constant for an ideal gas is not a function of pressure: But that is not generally true! Since: $$\left (\frac{\partial \Delta_{R} G}{\partial p} \right )_{T,\vec{n}}=\Delta_{R} V$$ and $$\Delta_{R} G^{0}=-RT\cdot \ln K$$ it should be: $$\left...

As per wikipedia, dynamic pressure is nothing but the expression of kinetic energy of unit volume of a fluid in motion. That's applicable to gases too. Question is, when a fluid is passed through a convergent and/or convergent-divergent nozzle, then its speed towards a specific direction...

Hi guys, I know the difference between these two things but I'm struggling with something that I hope someone could help me with. What dictates the water pressure needed for a "system" to work? I would imagine that if you've calculated your system to have a pressure drop of 1 bar (for...

Okay, my topic doesn't really ask a question but it is surprising to me that the old criteria of 273.15K and 760 torr are still being reported as the standard and very few websites have the "new" criteria of 750.06 torr. Are scientists, webmasters, etc. usually this slow at adopting changes...

I am making a small project at home for my solar panels. I have made a similar project when I was in school but I can't remember the equations. I want to attach an air compressor to a tube then install it on top of a solar panel, and pinch a few holes in it to clean the dust that accumulates...

On airplanes - do you know of a container or bag that will stops individual bottles with liquid from leaking/ exploding from the changes in air pressure?

Homework Statement E = 290 GNm-2 Yield Stress = 500 MPa Q. What pressure would a strain of 40 με indicate? Homework Equations Hoop Strain. εθ = 1/E (σθ − νσz) = 1/E (pr/t − ν(pr/2t). The Attempt at a Solution I am looking for some direction on how to determine the poisson ratio...

In "Sado Adachi" book "Properties of Group-IV, III–V and II–VI Semiconductors" page 222, he reported that "both εs and ε∞ decrease almost linearly with increasing pressure", however i was not able to find any empirical formula to describe these relationship for materials InAs, InP, InSb, where...

Homework Statement I need to find the amount of H2 being lost to water by being stored underneath a column of water. About 16 mL of H2 is made and it displaces the column by 16 cm. However the total amount of water is 30 ml/30 cm. I'm not sure which relationship to use to find the pressure of...

Hey All, I have a plastic vessel fully filled filled with an incompressible fluid (Water), at some time this vessel is impacted and crushed on one side (say 5% of the initial volume is lost). Only, I know the volume isn't lost, the fluid (being incompressible) will exert pressure on all...

Hello, my questions is not so much homework, but a request for a definition. When we use Cv*dT to solve for dU (internal energy) in a constant pressure example, what is the order of the temperatures entered into dT? Is one to assume its final temp minus initial temp? I ask because it leads to...

Homework Statement Suppose a tube is filled with helium gas at a pressure of 0.11MPa and a temperature of 297K. If a piston of area of 400mm2 at one end of the tube creates sound by moving sinusoidally with a frequency of 60Hz, creating a wave with amplitude of 3.8mm, what power goes into (I'm...

Homework Statement Homework EquationsThe Attempt at a Solution i have done the first two parts but the third part confuses me i am assuming the current is flowing in the z direction then current is parallel to the magnetic field then why would there be a force acting on it ?[/B]

How much air pressure, from six 1inch in diameter pipes, would it take to lift something no more then 250 pounds about six to twelve inches off the ground?P.S. This is a personal question not, homework.

I have been involved in a fairly furious debate about a fluid dynamics experiment regarding the pressure of air passing through a tube attached to a moving car. It is similar in concept to the issue of whether or not an opening in an aeroplane fuselage would suck people out, where the opening...

I was wondering, if cooled sodium or rubidium atoms behave as bosons, can they also occupy the same space? I tried to google a bit, but as usual, articles throw letters like ##\beta##, ##s##, ##\lambda##, ##g## around without bothering to at least give them a name so I could search deeper. I...

I worked out about 7-10psi in the pipe. What do you guys think?

Hello, I am calculating pressure drop through a pipe using CFD, which will be validated with hand calculations and experiments for a project. When I take results from my software, I can either take the pressure at a specific point (assume the centreline of the pipe) or I can take an average...

recently my neighbors and I have been awakened by a loud noise that sounds like something is being released under high pressure. An intense vibrating sound that lasts 30-45 seconds. We live across the steet from a soda manufacturer and down the road from a natural Gas transfer station. Both are...

Homework Statement Homework Equations AV = AV P + 1/2*p*v^2 + pgh = P + 1/2*p*v^2 + pgh The Attempt at a Solution For a.) ... divide 3 by 0.1 because of (AV = AV) = 30 ms-1. answer is right. For b.) I am stuck on this one. I tried using the 2nd relevant equation above but i can't seem to...

The condensate drain from a steam condenser is expected to be about 50 deg C. It's only 38 deg C or so. There's a mix of steam and non condensable gases coming into the condenser. Its pressure seems slightly higher, being about 0.25 bar abs instead of 0.2 bar. What does it indicate? Also, no...

Here is what I want to know specifically: if I replace my 5cm wide rear tire with a 6.25cm wide tire, how much can I increase the inflation pressure to obtain the same comfort? I realize "comfort" is not a quantifiable measurement, maybe shock absorption characteristics is better. Perhaps it...

Hi all. I am new to this site and I would like to verify the following calculation. Is it correct to do it this way? Please advise. Thanks. Hydraulic Press: 15 tons (Enerpac RC1510) Gauge Max Pressure: 10000 psi Actual Gauge Reading: 2500 psi Actual pressure (tons) = (2500/10000) X 15 tons =...

Homework Statement Homework Equations Radiation pressure i.e.R.P is the instantaneous pressure exerted by radiation on a perfectly absorbing surface perpendicular to the propagation vector of the radiation. Maxwell has shown that R.P = u , (1) where u is energy density R.P = F/A, (2) F...

Hey guys, so I stumbled across this, and I'm kinda confused on how do they get the sign convention of the value. I've attached the figure and also the soil pressure for better reference. Take for example at C, how do they get the minus and positive sign convention? Thanks a bunch. P/S : Please...

Hi! I wonder what pressure is when there are no walls. The reason for me wondering this is that gas pressure actually is defined by change of particle momentum, like p=\frac{F}{S}=\frac{1}{S}\frac{dp}{dt}=\frac{1}{S}\frac{d2mv}{dt} So how can there be pressure without change of momentum...

I was looking online for some solution to my question, and they varied from explaining it using potential energy to pressure equalization between the floor of the liquid between the bases. I still cannot seem to find my groove with this one. Tackling the pressure explanation, someone said that...

I have a relatively simple design problem but my memories of thermodynamics are very rusty and I can't figure it out on my own. To make it short, I want to put a mix of solid, water and air in a 500mL pressure vessel and heat it all up to 250'C for several weeks. T and P are at room conditions...

Hi, As per my observation and experience, when we use evaporative cooler to cool the inlet air to the gas turbine, the compressor discharge pressure (i.e PCD or P3) rises. As, the temp. of the inlet air drops and the mass flow increases due to the increase in density, I believe the discharge...

How do you account for the conservation of momentum for a photon? Specifically, if you have light traveling in a medium where the refractive index is not constant. For example, a graded index multi mode fiber optic. So here is another diagram to help articulate my question. Inside this graded...

I am a non technical innovator trying to develop a new product. Can someone help me calculate pressure drop and flowrate across a cylinder packed with uniform spheres of 10mm diameter. I found this online but unable to calculate...

Homework Statement The volume displacement in a car engine is 2000 cm3. During the power stroke, the mean pressure inside the cylinder is 15 bar. Compute the work performed by the engine in one revolution. Compute the engine's power assuming it runs at 3000 rpm. Homework Equations...

Hello, I'm studying dielectric barrier discharges (DBD) at atmospheric pressure. I'd like to have some references on highly collisional sheaths in radio-frequency discharges. I know the treatment becomes very complicated and one usually uses kinetic simulations, but nonetheless I'd like to see...

Assuming that the temperature in the tire suddenly rises. My question is that would that cause the contact surface area between the tires and the floor increase, decrease, or stay the same? (given that the volume of air in the tires is a constant and cannot be changed) Also, why?