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Questions tagged [air]

Earth's atmosphere is a layer of gases that surround it, permitting life and protecting life by absorbing ultraviolet solar radiation, warming the surface by retaining the heat and mitigating the temperature difference between day and night.

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Variation of fan air temperature with angle

On a very hot summer's day, I was on my porch using an electric fan and I noticed that the air it blew had different temperatures. As you move away from the center and towards the outer border, I ...
Tony Rodgen's user avatar
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3 answers
55 views

Does compressing air increase the average speed of the air molecules?

If you have a cubic foot of air and compress it, will the speed of the molecules stay the same or increase? I know that the air will heat up the surrounding objects because the molecules are in a more ...
Wyatt's user avatar
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-3 votes
2 answers
181 views

What would happen if a human completely disappeared?

How strong effect would roughly human sized and shaped vacuum spontaneously appearing at sea level have? This event is completely fictional. This is related to: What would happen if a piece of matter, ...
ingotangjingle's user avatar
1 vote
0 answers
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Hot dust contribution to whirlwinds forming

My father observed an event with a whirlwind and had an aha moment on its forming. What he saw was a weak wind blowing over a sun heated patch of dust, and when the dust rose up, all of suddenly a ...
Nemanja's user avatar
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8 votes
4 answers
2k views

How does energy become sound?

From my understanding energy and matter are interchangeable ($E=mc^2$). Also, motion requires energy, but energy does not require motion. Now, for my question, as an example, I will use the chain of ...
Emotion's user avatar
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2 answers
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Balloon volume as it rises in constant atmospheric density

I've been considering an hypotetical situation and it's making me a bit confused. If anyone could give me any insight, I would really appreciate it! It is as follows: Let's pretend atmospheric ...
oquiefine's user avatar
0 votes
1 answer
31 views

How does the rate at which we enter air at lower pressure affect whether air bubbles will get stuck in our blood?

When we, for example, scuba dive, we will breathe air at higher pressure, hence the amount of dissolved gas in our blood will be higher (Henry's law) (right?). Now when we come back to normal pressure,...
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1 vote
2 answers
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Is it possible to calculate weight with air pressure?

i was wondering if it was possible to calculate a mass of object on top a bag filled in with air as compared to a bag of air filled up with nothing on top of it assuming the air pressure going into ...
Kelvin Tan's user avatar
1 vote
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For hot air at 150 °C have a density of 0.61 kg / m³, how to calculate the density for 160 °C? [closed]

I am working on a project draft and in an existing device, hot air up to 160 °C is generated for drying processes. I have found old documents where densities of air are reported at three different ...
Esat Becco's user avatar
6 votes
8 answers
4k views

Can I get burned with warm air?

If temperature is the "average" result of measuring a mix of hot and cold air particles, then I can be in a room of some warm temperature but being hit with both extremely hot particles and ...
user1589188's user avatar
1 vote
1 answer
57 views

Formula for air density given temperature, pressure, humidity

What is a good formula for air density (kg/m^3) given temperature (°C), pressure (hPa), and relative humidity? I tried implementing the formulas from here as follows: ...
feetwet's user avatar
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How to determine air flow required? [closed]

I am making a sound dampening box for a vacuum pump. It’s loud almost 96dB. I have an ultra quiet fan to vent heat out of the box. I want to calculate how to make a couple small inlet holes while ...
Evan Guengerich's user avatar
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1 answer
124 views

Why does the density decrease equal the speed gain at Mach 1?

In this answer, it says : "At small Mach numbers, changes in speed cause negligible changes in density, but as Mach approaches unity, both are of similar magnitude. With Ma>>1 , changes in ...
Wyatt's user avatar
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0 answers
25 views

Does air gap between enclosed chamber and manometer influence the manometer reading?

We have an enclosed chamber filled with water. From the top of the chamber there is a metallic tube connecting the chamber to a monometer. We increase the pressure of the water inside the chamber buy ...
Mikael Arian's user avatar
1 vote
5 answers
150 views

Is there a way of changing air refractivity?

Is there any kind of way/equipment that can change the air refractive index? For example, a mirage is hot air refracting light in a certain way, making it look like water. The best I could think of ...
Fulano's user avatar
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1 answer
101 views

How to maximise air flow in a pipe?

I have a pump provinging a constant airflow through a pipe with a diameter of 3 milimeters. The pipe will then Go trhough a larger pipe with a diameter of 11 milimeters. I have the possibility to ...
Asd Ttt's user avatar
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Funneling air into a small opening, calculating time of speed differential

Assume I have a funnel that fits a rectangle air vent of 1" x 4" with an opening for a circular tube of 0.5" diameter. After connecting a 0.5" diameter x 2 ft tube to the funnel, ...
Jchen's user avatar
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1 vote
3 answers
257 views

Does food stay hotter if you keep air in the bag?

If I am taking takeout home in a plastic bag, is it better to remove all air from the bag when sealing it so no heat is lost to the surrounding air or keep air in the bag acting effectively like ...
reesespieces's user avatar
1 vote
1 answer
12 views

How carbon water filter can build air pressure inside (before installation)? [closed]

Today I got a new refrigerator carbon water filter. Before installing, out of curiosity, I dripped a bit water into the filter’s outlet to see if water could flow in and out. Obviously it did… Then, ...
max sim's user avatar
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0 votes
1 answer
29 views

Will hot object near ceiling vent create more draft? [closed]

As in the picture, we have a room with vents at the bottom to let cold air in and at the top to let hot air out. Normally the air flow is limited by the temperature gradient (correct me if I'm wrong). ...
El Flea's user avatar
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1 vote
0 answers
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What does a dynamic-pressure loss coefficient of more than 1 mean (for eg air going through bend)?

Air flow (eg in a duct) has a dynamic pressure, and when the air flow goes through e.g. a 90°-bend the bend has a dynamic-loss-coefficient. The dynamic-loss-coefficient is used to calculate the total-...
user84635's user avatar
1 vote
2 answers
50 views

Does air pressure change at the same rate on high elevation land as in the sky? [closed]

Is air pressure the same in a place like Denver, which is a mile (1.6 km) above sea level, as the same elevation above actual sea level? Same question for 2 miles high, as in any number of mountain ...
Matthew Nichols's user avatar
1 vote
1 answer
60 views

Formula of cooling power of compressed air [closed]

For my blog on Trompe air compressors I am looking into uses that people could have with these compressors if they build one themselves (for big versions see this Ragged Chute Trompe). One of the uses ...
St. Jan's user avatar
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If a spacesuit cracks open, does the astronaut blow up due to difference of pressure? [duplicate]

Me and my friends had a discussion on emergencies in outer space. One questioned what would happen if a spacesuit ruptured and exposed an astronaut to vaccuum. One claimed that since there is no ...
okj122983's user avatar
2 votes
2 answers
538 views

Why does blowing air on wet bodies dry it? [duplicate]

Suppose I blow dry a region with some water on it. Would it dry it faster than otherwise? If yes, why? I can give one qualitative reason against it, since the blow dryer is blowing room temperature ...
Babu's user avatar
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3 votes
1 answer
51 views

Does a planet's "equatorial bulge" induce any kind of motions or currents in the atmosphere?

Rotating planets, like the Earth, are not perfect spheres but are instead oblates. This affects both the crust and the atmosphere, creating a bulge in the equator 1. I was wondering if there are ...
vengaq's user avatar
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0 votes
1 answer
72 views

How much deviation from ideal gas does the air in a 'Room' show?

First of all, I'm only concerned about air in a Room (room in our houses). Also, lets take room temperature to be $27^{\circ}$ C specifically. My first question is, how much different is this gas (air ...
Rohit Shekhawat's user avatar
0 votes
2 answers
46 views

What path will air take to leave the space station?

Hi everyone, lets say we have a circle shaped space station and there was an accident where we got a hole (hole A on the picture) on a station and now most of the station is vacuum except for one ...
Exe's user avatar
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0 votes
2 answers
176 views

Does EM wave lose energy in air?

Light is EM wave. As it travels through vacuum, it does not lose energy but I am wondering if it travels in air, just imagine light in your home. Before it reaches your eye, it has to travel through ...
Giorgi's user avatar
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18 votes
3 answers
3k views

Would an adhesive surface have more air resistance?

Imagine spreading double-sticky tape all over the surface of a car or a plane. Would there more significantly more aerodynamic drag as a result of the adhesive 'sticking' to air molecules and slowing ...
CPlus's user avatar
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1 vote
1 answer
328 views

What part of my oven should be hottest, top or bottom? [closed]

My oven has the heating element in the bottom. So the bottom shelf is more directly exposed to it, and should be the hottest shelf. But hot air rises, so the top shelf should have the hottest air, and ...
Juan Perez's user avatar
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2 votes
4 answers
443 views

What is the physical reason for why hot air holds more water vapour, and how does this relate to saturation vapour pressure?

It is said that hot air holds more water vapour. I guess this means that the saturation vapour pressure of water in air increases with temperature. Is this correct? How can one derive this result? ...
DeltaIV's user avatar
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1 vote
0 answers
67 views

Airflow between two rooms (one hot, one cold) [closed]

Scenario — It is night time and somewhat cold outside. Room 1 (Bedroom): The window is slightly creaked open. I have a space heater going on continually heating room 1. One door is closed to the ...
Garrett Fadul CrazyJalapeno123's user avatar
0 votes
2 answers
184 views

Lift and drag forces in parachuting

EDIT: guys, I am not a physicist and it is not my study field, So even if you see my question is silly to be answered, I hope you can give me a clue. I hope you are doing well. I have some questions, ...
f.alnayef's user avatar
0 votes
3 answers
577 views

How can I mathematically model the entrainment of air through a window?

The Problem Suppose I have an open window with an area $A$, and a uniform wind source (a fan) pointing towards the window, positioned at a distance $s$ away from the window. At the exit of the fan, ...
martinv's user avatar
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1 answer
47 views

Is the sound from a chimney fire the same as the sound caused by a fire inside a fireplace?

For a while now I've been researching the causes of why a fireplace fire makes a roaring sound, and from what I've read, it mostly has to do with the way air rises, creating a vacuum underneath, ...
HeavenlyHarmony's user avatar
0 votes
1 answer
81 views

Does the earth exert centrifugal force on us in air? [closed]

Whether the centrifugal force exerted by earth due to rotation be felt or even applied to us if we were in air ? The landmass rotates with earth so it is exerted on us radially outwards , but that isn'...
Razz's user avatar
  • 441
30 votes
7 answers
9k views

Why does blowing a whistle in someone's ear damage it more than blowing directly in their ear? Won't the whistle reduce overall energy?

If I blow really hard from a whistle near someone's ear, it'll hurt a lot. But if I blow directly at a person's ear, it won't hurt nearly as much. But shouldn't the whistle (or any other obstruction) ...
chausies's user avatar
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0 votes
0 answers
57 views

Would everything we see be delayed if light slowed down to 1ms?

I don't know much about physics, though it certainly interests me. so I apologize if this is a dumb question, but if we somehow slowed down the speed of light around us. (like we somehow made air have ...
Kaleb Clint's user avatar
0 votes
1 answer
128 views

Is there any physical explanation for negative extinction coefficient, $k(E)$, over a spectral range of energies?

Measured data for $n(E)$ of air were fitted to equations for $n(E)$ and $k(E)$. The measured data for n(E) spanned 0.734 to 6.702 eV. To obtain fits to the equations for n(E) and k(E) in the absence ...
Iris's user avatar
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0 votes
3 answers
85 views

Feeling of coldness in heights

We know that due to buoyancy the cold air sinks and warm air floats above it due to it being less dense than cold air. Then why do we feel cold as we go to greater heights/hill stations and feel hot ...
Naveen V's user avatar
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0 answers
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How does the slipstream of a falling object affect flying animals near it?

I am the script supervisor for a short film being created by several of my friends. In the script, it specifies that a bird is sucked downward by the passage of a large falling crate. I am now, ...
Aedan Ferrara's user avatar
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0 answers
24 views

Can pulling a door fast create air movement that causes heart pain, maybe considering weather pressure of 1035 hPa? How does it work?

Flatmate has a habit of using all his strength to open the door of his room, which is on the adjoining corner of mine. I feel like each time the air is pulled. Now it's winter, air pressure 1035 hPa ...
mario's user avatar
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0 votes
0 answers
187 views

Why is there a vacuum in the upside down glass and card demonstration?

In this Hila Science video on atmospheric pressure (https://www.youtube.com/watch?v=xJHJsA7bYGc&ab_channel=ScienceOnline) from 2:30-3:05, it shows the common demonstration of turning a glass of ...
suse's user avatar
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0 votes
0 answers
28 views

Would it be possible to use a device pumping air out of it to liquify the sand around it?

The question has to do with the demonstration done by Mark Rober when he made a hot tub by releasing air from below the sand upward at a rate that would increase the amount of air between the sand ...
Broc Stucki's user avatar
1 vote
0 answers
28 views

Airflow through tube

I have a tube with an inline fan moving 100 cfm (cubic feet per minute). If I add an additional fan in the same tube capable of moving 100 cfm, what would happen? Would I increase my cfm to 200? Would ...
Geo's user avatar
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1 vote
1 answer
112 views

Pressure over time in a tank with variable volume and an orifice

I have a tank whose one side can be moved, so we can change the pressure inside the tank by this movement. (In my main case this ig going to be a sinosoidal movement). We add an orifice to the tank, ...
Kristóf Németh's user avatar
1 vote
0 answers
59 views

How long will oxygen last in a $3\times 3\times 3 $ meter room for one person? [closed]

Let's assume that the windows and doors are tightly closed. How can I calculate at what moment I will feel a lack of oxygen and my well-being will worsen? Can one person completely consume all the ...
Tamila Ambeon's user avatar
1 vote
1 answer
46 views

Can a cold gas be considered as ideal at a very high speed?

Considering a plane flying in the atmosphere, my book uses the perfect gas law $pV=n\bar RT$. Yet, as the plane itself is taken as the reference, the air ($T=-50°C$) has a speed of $800 \ \mathrm{km/h}...
user avatar
2 votes
1 answer
120 views

Theoretically, how can you remove friction between surfaces with air?

I know that if there was a way to compress and control air (think air bender) then it can be used to remove friction between two surfaces. A person could just skate on their feet by focusing this ...
Star's user avatar
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