What is Air pressure: Definition and 209 Discussions
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325 Pa (1,013.25 hPa; 1,013.25 mbar), which is equivalent to 760 mm Hg, 29.9212 inches Hg, or 14.696 psi. The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is approximately 1 atm.
In most circumstances, atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. Pressure measures force per unit area, with SI units of pascals (1 pascal = 1 newton per square metre, 1 N/m2). On average, a column of air with a cross-sectional area of 1 square centimetre (cm2), measured from mean (average) sea level to the top of Earth's atmosphere, has a mass of about 1.03 kilogram and exerts a force or "weight" of about 10.1 newtons, resulting in a pressure of 10.1 N/cm2 or 101 kN/m2 (101 kilopascals, kPa). A column of air with a cross-sectional area of 1 in2 would have a weight of about 14.7 lbf, resulting in a pressure of 14.7 lbf/in2.
I wanted to inquire as to a thought I have on a situation with buoyancy and air pressure.
In the first slide (slide 1), I am showing a situation where a buoyant object is pushing up on a support wall through a fixed wall that has water in it. Here are the factors:
1. The net buoyant force of...
My dad and I were going to fill up a tractor tire that was very flat. We had two air tanks, a small (~5 gallons) and a large air tank (~10 gallons) which were both filled to the same pressure (~100 PSI).
We wanted to pressurize the tractor tire as much as possible with the two tanks, and so my...
Hello Everyone, I am working on a project with a friend and neither of us have any formal training in engineering but we generally are quick learners. We are both familiar with many of the gas laws and are trying to calculate the equalization pressure between 2 cylinders/vessels or tanks used in...
My question is harder to explain than I would imagine it will be to answer. I'm trying to vaporize a non-combustible fuel source with an internal radiant coil surrounding a small vaporization chamber consisting of a heat-resistant cotton-like material being fueled by a constant drip fuel pump...
Given the following situation:
Given that A is air tight how would one go about working out the air pressure required to achieve:
Any assistance would be appreciated.
Homework Statement
We have a pipe open at both ends and having the length of 1 meter. After putting it into a tub of Mercury and thus filling it to the half, we close the upper end of it, and then remove it from the tub. What is the height of the residual column of the Mercury in the pipe...
I have a physics question about slamming doors and explosions. I've heard before that an explosion releases shock waves through the air that can severely damage a person's vital organs. Recently, I had a door slammed in my face (not literally, it did not hit my face). This wasn't a normal "door...
hello, I'm wanting to make an air pressure cannon and am trying to mathematically find out how to get the highest muzzle velocity, could someone please check over my working and let me know of any mistakes and perhaps offer suggestions on how to improve my cannon.
if my maths is correct am...
Homework Statement
What is the headspace pressure (air)?
Closed tank part filled with fluid under pressure, there are tubes that indicate the fluid level and pressure. The tube on the left is open to atmosphere.
fluid s.g. 1.2
x = 5m
y= 1.7m
Homework Equations
See below
The Attempt at a...
Ï had not the slightest idea there was even a cool place to learn about science and physics and...truth! I'd usually just "Google"it and read Wikipedia. One of the main things I would like to learn about would be air pressure or flow, air density and maybe some rotational mass. So let's say in...
Hello everyone,
It's my first time posting, so I hope everyone is doing well. I am looking for some help for a high school research paper/lab I'm currently working on. Basically, I am investigating how the varying air pressures of different baseball parks have an effect on the distance traveled...
we know that air pressure on our Earth is 1 atm.
Also 1 atm = 10^5 P
Also we know Pressure(P) equation = P = F/A So, F = P*A
So if small area(A) in which we are standing is also taken then pressure force is that area(A) times 10^5(Atmospheric pressure in Pascal) i.e 10^5*A
So why don't we...
Of the few occasions I've seen Airfoil Lift described to general audience (on documentaries), it has focused on the top-side curve of the Airfoil causing air on the topside to move faster than the bottom-side. This is said to reduce air pressure on the topside and result in lift.
If a wave is...
Hello all! Can you please provide some guidance with this problem?
1. Homework Statement
Calculate the air pressure at 3000m above sea level assuming that the molecular weight of air is 29 and the ambient temperature is constant against height.
Homework Equations
Stokes-Einstein equation. In...
Hi everyone,
I've got a newbie question which is probably more complex than I imagine so please bare with me. As a small DIY project I've trying to build a small exhaust filter system (A) for another device that produces undesirable fumes (B). I'm trying to work out if an axial fan (generates...
In a thermo flask the air between the outer and under wall is sucked out and a vacuum is created. So the air pressure should push the outer wall towards the inner wall and vice versa. But it doesn't happen. Why?
1. Is the pressure inside a building equal to the outside? Is there a very tiny difference?
What about air-tight room?
Homework EquationsThe Attempt at a Solution
How to calculate how much flowrate from blower i can push water pool 2,75m*1,8m down by 1,25m in 1 sec?
Note : Blower Pressure 0.03 bar - 0.035 bar
There is an empty room above the water pool with dimension of 2.75m*1.8m*1.7m
This process happen in a closed chamber...
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So, how does Air Pressure 'works' on Earth.
Would this right to say that, the air molecules present in the atmosphere are forced down due to gravity and thus applies force on every object downwards towards the Earth's core thus causing Air pressure?.
Another question I would like to know...
There is something confusing me about air pressure inside balloons. I got three questions:
Assume I am sitting at sea level, with a balloon. I fill it to 1/3 its capacity with air.
Then I place an absolute pressure sensor at its opening.
1- What pressure value do I read ?
Do I get the 1013...
Hi, I'm working on a project and need a bit of help, since I don't want to kill myself.
My question is this: If I have a cylindrical tank (think a big scuba tank) half full of liquid, half full of gas (let's just say it's water/air) and start heating up the liquid, I know that pressure will go...
I have a pressure regulator that has working the range of outlet pressure 0 to 2 bar, inlet pressure 5 bar, flow rate of 600lit/min and the regulator has 1/4" outlet port (6.35mm). whole data is according to manual I have not tested the regulator. But for flow rate of 600lit/min the velocity...
Hi guys
Im trying to understand something..
If air is coming through a pipe, at a variable fan speed. (0.0053 m3/s) and the pipe is 10 meters long and coiled.
Will the air reach the end of the coil?
Or can air just loose pressure at a certain point?
Thanks!
I have an air leak somewhere in a coil or 20 feet of pipe in a mechanical room next to a transformer. I have 160 psi of air on the system and it dropped 30 psi in two days.
I have tried to find the lead with 60 psi of water currently but no success. I do not want to put a lot of water...
1.The problem I have been facing is understanding how a straw exactly works ?? I know the general, conventional solution given to this problem by the principle of working of a barometer, but I think it has a serious loophole.
3.They say as a vacuum space is created in the straw due to our...
Hey people, first post, I'm sorry if I'm posting this in the wrong place.
How do you calculate the force exerted on a sphere? I'm building a pneumatic air rifle, and I'm trying to figure out how fast an airsoft bb accellerates with a certain pressure.
The projectile is 6mm in diameter, so...
Hi!
I have a question.
The experiment goes like this. i hermetically close air and chloroform at standard pressure. now i want to calculate the end pressure of gas mixture after chloroform vapor gets saturated.
is it as simple as adding up the chloroform saturated pressure to the starting air...
I am looking at air system that is under a constant pressure of 350 mbar into a pipe that has 40 - 2 mm round holes. Is there a formula that I can use to calculate the total volume of air nm3/hr that will escape the system?
Let's just say the air temp is constant.
Can anyone help with this?
the barrel has a lid at the top...sealed. I make a hole at the bottom to attach water hose to it. Then I turn on the water hose. The water volume in the barrel increases, no doubt about that. When It takes 7/8 of the barrel. Will the air in the top 1/8 of the barrel be compressed? I ask because...
i have a pre made tank approx dimemsions 3x3x3 feet the thickness of tank walls appear to be 3/16 to 1/4 inch thick. with a 1foot square opening on top for filling this opening had a raised "wall" approx 2inches. tank is used to collect used oil for shop heating. (this tank looks like a...
Hi,
I am wondering if anyone can help me out with this, I'm looking to create 130.5 PSI of Water pressure for 15-20 seconds. If I were to pressurize an air chamber what size/volume would be required to achieve the above? Or would it be better to directly pressurize a chamber with water...
Air pressure decreases at a rate of 2.5 pascals per kilometer in the eastward direction. In addition, the air pressure is increasing at a constant rate with respect to time everywhere. A ship sailing eastward at 10 km/hour past an island takes barometer readings and records a pressure drop of 30...
Consider the following:
I have 2 PVC pipes, one is small enough to fit into the other with a little extra space. A rubber ring is placed around the smaller one to fill up the empty space, making a good seal to push air in and out of the larger one. Ignore any friction caused by the ring on...
Okay, so I am looking at this article (link at bottom) and it says they have a microorganism liquid contained inside of a CLOSED steel pipe fitting and they heat it until it's reached about 570 degrees inside.
SO HOW MUCH PRESSURE GROWS INSIDE THE CLOSED CONTAINER?
As far as a real life...
Correct me if I'm wrong I'm only 15. But doesn't air pressure affect the speed at which is needed to make a crack/boom. If so it would be easier at 50k feet to go faster, but you would not created a cone until you reach a higher speed. And vice versa with say. 5k feet.
I am doing a research project about wind pressure and the different uses one can achieve by changing the pressure, volume and speed. I am comparing a hot air balloon ride vs an air plane vs human flight. I am looking and what minimum and maximum MPH is needed to achieve human flight and with...
hey guys! I'm really confused as to what this question is trying to ask me!
can someone help me out :)
Air pressure decays approximately exponentially at about 0.4 per cent for each rise of 30 metres above sea level. If we let p = p(h) denote air pressure (measured in some appropriate units) at...
I am a property manager and I have a building that is 1 story, with about 20ft of space from the drop ceiling to the roof. I have two exterior doors that when opened, cause a major draft of air blowing in from the outside. This causes comfort issues in the summer and winter and then also causes...
The question asks; "Assuming that the density of air is a constant 1.3 kg/m3 and that the air pressure is 1 bar, what is the pressure at the top of a 500 meter high skyscraper?"
I'm having trouble setting something up but here is what I do have;
Regarding liquids we know that F =...
Hello all,
I was thinking about situations in introductory courses or textbooks where pressure or buoyant forces are suddenly introduced in situations where they become relevant which lead me to think about the consequences of neglected said forces in more elementary problems.
I'm curious as...
Hi!
I have a very hard time grasping the pressure concept.
Look at normal air pressure (1atm)
1atm≈10^5Pa=10^5N/m^2≈10^4kg/m^2=1kg/cm^2
In other words, one whole kg per square centimeter!
How can this be?
I don't feel the air pressing against my body with one whole kg at each...
Homework Statement
Consider the electromagnetic radiation inside a kiln, with a volume of 1 m3 and a temperature of 1500 K.
Calculate the radiation pressure inside the kiln. How does it compare with the air pressure?
Homework Equations
PV = NkT
The Attempt at a Solution
I got...
Hi Everyone,
I'm interested in a formula posted in an invention patented 30 years ago for a Tornado Type Wind Turbine. The wind blows through an opening in a tube shaped tower and is turned onto itself. This causes the wind speed to increase to three times the ambient wind speed (and the...
Hi, could someone please tell me if the vapor pressure should be combined with the air pressure in a sealed vessel to give the total pressure? For example, if I put room temperature water in a test tube (at sea level) with some head space for air and then seal it, the pressure inside would be 1...
Homework Statement
I'm trying to calculate the air pressure from some data that I have.
#1. Calculate the cylinder pressure. (barometric pressure=765 mmHg, h=35mm)
#2. Calculate the moles of air using low temperature and volume and cylinder pressure above. (Low temp=50.0deg Celsius...
Hi there,
I have a peculiar question. Imagine that you are in a Earth position, obtained by google, that gives you the latitude and longitude. Those values are given in the decimal notation (ex: lat=20.44 ; long=-8.5).
Now imagine that you want to know the air pressure in your position...
I am having a problem with an air pressure drop. I have a supply of 100psi of around 4scfm. I have it regulated down to 90psi, but when I turn on an air turbine motor my regulated pressure drops momentarily (1-2sec) down to 80psi. This drop in pressure is unacceptable to other components in my...