Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled gage pressure) is the pressure relative to the ambient pressure.
Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre (N/m2); similarly, the pound-force per square inch (psi) is the traditional unit of pressure in the imperial and U.S. customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the atmosphere (atm) is equal to this pressure, and the torr is defined as 1⁄760 of this. Manometric units such as the centimetre of water, millimetre of mercury, and inch of mercury are used to express pressures in terms of the height of column of a particular fluid in a manometer.
How is it that once the dew point is reached, moisture continues to condense. What is causing the imbalance of partial water vapor pressure?
Does the rise in atmospheric temperature simply pass up the evaporation rate too quickly?
If you have two different containers filled with two different gasses at the same temperature, would they have less pressure when connected to each other?
Dalton's law states that each of the gases behave independently when it comes to pressure as they fill the space as if they were the only gas...
Hello all, I am posting this question here in this thread and not the homework thread since it is not a homework problem but something I have been working on myself.
Let us imagine a fluid flowing through a pipe, we can measure pipe diameter and fluid velocity. The density of the fluid is also...
Morning all,
I am working on a Air Cannon Project and have hit a stumbling block.
I am trying to work out what tank pressure and volume I would need to project a 1.4kg mass to 83m/s when it leaves the barrel.
The barrel the mass will travel down is 4 meters long and 6inch in diameter, would...
Homework Statement
In a lecture demonstration, a professor pulls apart two hemispherical steel shells (diameter D) with ease using their attached handles. She then places them together, pumps out the air to an absolute pressure of p, and hands them to a bodybuilder in the back row to pull...
I'm an empirical sciences student who loves physics. While studying geology I learned that the core of the Earth is considered to be solid and the reason for that is because the pressure is too high. Although according to my calculations g( gravitational field) equals zero and when you go out...
It seems like a simple question, with a simple equation, however, what is force of pressure of a sting of a mosquito on the human skin? Does it possible to evaluate, because I haven't found ANY required data, even though, I have a formula P=F/A
Hi PF!
Can someone help me understand how to draw lines of constant pressure in an inviscid flow field, say flow around a cylinder. I am having trouble understanding how to draw these. Any help is greatly appreciated!
I ask this question because I am preparing for the Q exam for PhD and one of...
I'm trying to compile a complete list of available humid air density formulas that work with air pressure, temperature and dew point (or RH).
If you know any, please advise.
Thanks,
Robert
I've been wondering how I can find the pressure water exerts on a sphere it's in.
As for cyllinders and pyramids, and prisms - the thing is extremely easy - you just take the one formula and put in numbers.
What about a situation when we have a sphere whose radius is R, and it's half full with...
From reading textbooks, we just know that there is a pressure difference because the fluid speeds up. But WHY is there a pressure difference, why does the pressure decrease?
Suppose we have a pipe of some length ##2L## and at the ends there is to spherical caps of fluid, as shown in the attachment. Is it possible for the two ends to have different curvatures in equilibrium?
My initial thoughts are no, since pressure is proportionate to curvature (Young-Laplace) and...
I have a centrifugal pump 50 m above a vessel, I’m pumping water in at 4 bar gauge into this vessel. I then close a valve to cease pumping ensuring no air enters the system.My question is, if I now open that same valve to atmospheric air this time, will the water exit from the pipe through the...
Here is the scenario.
An astronaut is conducting experiments inside of a laboratory module within a space station when all of a sudden, a fire breaks out. The astronaut escapes from the laboratory module he was currently using and then proceeds to seal it off using an airlock.
He then...
If we have some pressure/stress (say 1 atm) applied to an end of a square rod. Let's say this square face expression this pressure/stress is discretized into 4 squares of equal area. Each each sub-square experience 1 atm or 1/4 atm?
I'm trying to figure out how to best filter some liquids. A 5 gal bucket is filled with some filter medium (say sand on top 1/2 and fine charcoal on bottom 1/2). The liquid is slowly added at the top and gravity is used and vacuum may be used at some point with a complete seal along the bottom...
Im currently trying to calculate the pressure inside an injection mold. Does anyone have experience with similar problems? I need to use coeficient of Thermal expansion and volume. please help .
Hi, I'm trying to do some figuring on vapor pressures. If one were to take two plates heated to 220F and press water between them in a press that exerts 100psi, what would the resulting vapor pressure of the water be?
Now, what temperature would you heat the plates to if you were using a press...
I am not tech savvy. But I like to solve quiz relates math and physics.
I was solving such questions and come across this question.
"On a cloudy day, a sealed packet of potato chips is taken to the top of a mountain. The packet is found to be blown up like a balloon."
What is the reason...
I have been studying structural physics lately, in particular the linear elastic eqns, governed by the equation of motion. https://en.wikipedia.org/wiki/Linear_elasticity
I am trying to solve these equations numerically. I was thinking of a scenario of a rod being compressed on one end by some...
I'm an engineering student, one of my task is to search the best orifice type for pressure drop. I have no idea which one would it be since I believe that the beta ratio is the one that would determine the best orifice for pressure drop.
How do I calculate the gravitational mass of a cylinder of compressed gas, including the effects of pressure? By gravitational mass, I mean what I would measure on an ideal mass balance.
(I know that the pressure is negligibly small in a realistic container, but I want to have a conceptual...
I'm in the process of designing a part which must be submerged down to 2000m (200 bar/20 MPa/ 2900 psi). A sketch of the part has been attached. The outer housing will be titanium and the inner part aluminium. I've carried out the calcs for the outer part to withstand the external pressure, but...
Hello, I'm a physician with special interest in cardiovascular physiology. I'm trying to comprehend the basic physics of the cardiovascular system. Here's my thought process -
Simply stated - the heart muscle contracts, thereby causing a reduction in the cardiac chamber volume and release of...
Homework Statement
X and Y are two gas bottles that are connected by a tube that has negligible volume compared with the volume of each bottle. There is a valve in the tube that is initially closed. X has a volume of 2V and contains hydrogen at a pressure of p, Y has a volume V and contains...
Why is the pressure used in flow work the pressure of the fluid? If the fluid was say at 10kPa and the external pressure was at 0Pa, why don't we use the 0Pa in our calculations for flow work, since it's the external pressure that's the resistance? Or is it not possible to have this difference...
Hello everyone,
I have a question about a common rail high pressure pump.
Most common rail pumps make use of a pressure control-valve which controls the amount of fuel that goes to the plunger. This way it is possible to control how much fuel goes to the rail, so it controls the pressure...
I have been wondering about how Propane is stored in a liquid state at 12 bar in cylinders. If a cylinder of propane was connected to a cylinder of the same size that was not pressurised would the pressure then across the two cylinders be reduced to 6 bar and the propane possibly expand? If this...
In small Fission reactors it can be hard to get enough heat in order to boil the water inside the boiler, so why don't we create low pressure boiler systems, where we can boil water at slightly above room temperature, use it to turn the steam turbine as it flows to the similarly low pressure...
Homework Statement
In a sealed container is Helium ##M_{He} = \frac {4kg} {kmol} ## with a pressure of ## p_{He} = 4bar##. now is Methan put isothermic inside the container till both the methan and the helium mass are equal( ##M_{CH4} = \frac {16kg} {kmol} ## Calculate using the ideal gas law...
Homework Statement
P(average) for a speaker is 10 W. Gamma is 1.4 (ratio of specific heats), molar mass is 28.8 g/mol, air temperature is 50F, and pressure is 1atm. Find Pmax at 100
I have this equation that gives Intensity = (Pmax^2)/(2*Rho*v) where rho is density, and v is speed of sound...
Light has no mass. It has a momentum, though. That means it can potentially push things when reflected and therefore lose energy due to the doppler effect, right? Does it mean that it gains energy when it slows down things and doesn't lose any energy if it doesn't push anything? If the whole...
Homework Statement
Hi, Iv got to find the minimum diameter of a pipe if the pressure drops in a system is to be limited to 0.3bar. when delivered through a pipe of equivalent length 160m
I have to use the formula
Pressure Drop = 800lQ^2/Rd^5.31
I believe I have to transpose this to find...
Hi,
I have a pipe that is unpressurized initially at atm internally with air. Inside the pipe there is a welded container that is vented at the top. The vent is made to have air pass through so that the internal pressure of the container eventually equals the pressure of the internal pressure of...
So, a coworker approached me today with a 'simple problem' to solve, looking to sanity-check a design choice.
Much to my dismay, I had no idea how to approach it. Worse, google had no straight-forward answers either, and any formulae I did find seemed circular.
This seems too simple to...
is the amount of argon gas to exert 10,000 psi in cylinder will be the same if argon transformed to plasma or the number of moles will be less as plasma is more excited and have higher kinetic energy?
I simulated an incompressible turbulent flow across a tube. I managed to solve it using OpenFoam and the results seem to be right. However, I noted some vacuum pressure after the sudden expansion but can't figure out why the pressure decreases and then increases again. According to Bernoulli's...
Vacuum bags are used to infuse various things with liquid resins such as fiberglass or carbon fiber. It seems that the higher the vacuum the better (and possibly faster) the infusion works. Could it be more effective to use a vacuum bag and also have the entire bag in a pressure chamber to get...
Homework Statement
We wish to heat water from 10 °C to 50 °C using vapor at 180 °C and 1.5 bar of pressure. How much cold water do we need to mix with every Kg of vapor to obtain the result?
Homework Equations
I am not sure. I think the problem is related with exergy and energy balance
The...
Hi All,
Is there anybody who can help me with this question?
Example:
What is the enthalpy of CO2 in 200psig and 80deg.F?
I have a software, but I'd like to see the calculation steps.
Thanks
Ding
Homework Statement
The electron density per area, ##N## for a gas layer of thickness 10 cm can be determined
$$n = k \times p \times 2.47 \times 10^{19}$$
For each adjacent sets of pressure data using Matlab, calculate the average energy in keV, the pressure difference in hPa, the energy...
I am a software engineer. I am working on an experimental project to attempt
to measure in real time the variation in air pressure (relative to the ambient
pressure of the room) in a piston style apparatus. In this model, I am expectant that there will be a measureable change in the internal...
Since pitot tubes measure total pressure from the flow ramming into the total pressure hole, could I use any thin piece of pipe facing the flow (given that it's smooth on the inside) to measure total pressure? Trying to think of ways not to use my pitot tube to measure the total pressure of a...
Homework Statement
A 3-m3 rigid vessel contains steam at 10 MPa and 500 degC. The mass of the steam is?
I know this question involves using a thermo-table, I'm just very confused on how to find mass from the given information.
Homework Equations
Maybe PV=nRT
The Attempt at a Solution
I...
I'm trying to optimize a system involving one or more propellers / fans driving air through a packed bed for scrubbing (compressed then expanded) and out the other side to achieve propulsive thrust. So there's going to be a pressure drop in the slipstream. I've already set up a system to do the...
Homework Statement
a)Consider the vessel in the figure shown. It contains a liquid of density p. Calculate the pressure, and give the direction of the force on the container due to the liquid, acting at each of the following points.
b) Consider the second figure shown. Why is the pressure the...