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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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Relationship between CO2 concentration and thermal conductivity of the air in a volume?

How much would the percentage of CO2 in a room need to change in order to make a measurable change (using transient hot wire method) to the thermal conductivity of the air inside room? Are there other ...
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How to generate force with air pressure [closed]

I am trying to figure out how to generate a substantial force for a short period of time by releasing pressure in a small high-pressure air tank. A rough estimate of the force required is 40 ...
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How do you reckon my mattress works? [closed]

So I have one of those "sleep number" mattresses, made by Select Comfort. Good mattress. It contains two air chambers, and has a pump which can inflate or deflate these air chambers to the desired ...
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Finding the drag force from the final velocity of a falling object

I know the velocities (v) of an object after it fell for respective distances (s). From that alone, is it possible to calculate the drag force at a specific moment in time? If not what else would I ...
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Water / Air flow via thermal difference

This is a simple water/air flow thought experiment I had that I'd like to understand better... The basic idea is that you have a closed loop of water or air standing vertically. One side is heated to ...
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Do CFCs get emitted in air from appliances?

Do the refrigerators and air conditioners that use CFC or HCFC cause damage to the environment even when they are working normally. I mean, is there any gas emission under normal conditions when the ...
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Why are we able to see air bubbles under water?

Title is self explanatory. I'm assuming both water and air are transparent. So, if they are true, how can I clearly distinguish an air bubble under water?
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When is it more efficient to blow air over a wet laundry in order to dry it - when it's wetter or when it's drier?

If I want to speed the drying of laundry and allocate for it one hour of fanning - should I use it just after I hang it to dry or several hours later? When we want to cool hot tea it's better to add ...
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How does flatulence travel through the room when opening a window? [duplicate]

When the smell in my room seems to be full of flatulence(it wasn't me), what happens with the gases when I open a window? Detail: It is winter and the air outside is cold whereas the air in the room ...
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Increase Air Speed at outlet

I have a set up that inflates a rubber jacket in order release the metallic rings from underneath it. I am currently having issues with not having enough pressure (force) at the outlet to inflate the ...
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Why do thermal currents affect light but wind does not?

I notice if I put heat under a laser beam it will cause the beam to shimmer. The heated air is causing a disturbance in the air which affects the light. Yet, I can blast a stream of air from a ...
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Simple experiment proving air pressure is stronger than water pressure at sea level [closed]

I conducted a simple experiment I: pour a little of water into a cup, put a card on top & turn all upside down. The card does not fall $\Rightarrow$ $$P_i + P_w < P_o\tag{1}$$ $P_i$ : air ...
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Tire pressure physics

I understand that with less tire pressure you get more surface area on the pavement and more friction which gives more rolling resistance, but does having less air mean that there’s more weight per ...
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Can we see stars in day time by making use of a blue notch-filter?

Given on a clear sunny day, the only light that is blocking the star light is the scattered blue light of atmosphere. If we make use of a notch filter, which blocks only the blue light, can we get ...
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116 views

Initial acceleration concerning free fall

I'm in the process of conducting research concerning free fall with air resistence. I'm dropping a beach ball filled with air from certain heigts, while measuring its speed and acceleration during the ...
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How is steam affected by a fan?

Scenario Consider a humidifier with a fan behind it. Assume same room, moderate temperature, low fan speed. ...
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How much pressure is needed to create a can of compressed air duster?

First, I asked this question because I want to take advantage of a can of air duster cooling ability So if I want to make a can of air duster, how much pressure do I need? Can I use regular air ...
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Hydrostatic pressure in a gas

I have a physical picture of hydrostatic pressure ($dp/dh = \rho g$) in liquids, interpreting it as the weight of the water column. Now in a gas, the molecules are much further apart than in a liquid....
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How to understand air pressure against a hand pump?

Imagine this little though experiment with me for a moment. A piston sort-of contraption - like a bicycle pump, but without any nozzle to push air out of. One foot tall, one inch width/depth. Lets ...
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For a lay person, what if there was no atmosphere? [closed]

What if there was no atmosphere (or little like on the moon)? Could I then hover above and watch the Earth below turn? Originally I queried, "why couldn't a person just float up in a balloon, hover ...
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2answers
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Air velocity flowing out of a pierced can [duplicate]

How can I calculate the velocity of air that would come out of a pierced can of compressed air if I assume that the pressure inside the can is 7 atm and the size of the hole is that of a regular nail?
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Why does the water pressure initially drop then stabilize when pressure testing a valve?

Sometimes the dropping goes on so long(10-15 minutes) that the test is thrown out and the valve is opened and filled with water for a longer period of time. Pressure testers claim that it is because ...
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Simulating scintillation (twinkling)

i would like to set up a small lab experiment to try to create visible "terrestrial scintillation", whereby one can see fluctuations in air density (turbulent air), like the rear of the jet in this ...
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Why can't hot air balloons fly higher then helium balloons?

I have read these questions: Hot air balloon trajectory predictions Do atmospheric physics prevent hot air balloons from ascending over 60,000ft? What is precisely the reason that a helium balloon ...
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Moving a marble in a maze using wind force

For a school assignment, I have to write a game where you can move a ball through a maze by generating unidirectional wind when the mouse is clicked. The ball is on a flat surface. The concept is ...
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Sound pressure levels: Why doesn't blowing in someone's ear cause hearing damage?

Quoth Wolfram Alpha: 5000 Pascals ≈ 0.51 × lung air pressure that a typical adult human can exert (≈ 9800 Pa) ≈ 50 × sound pressure at the threshold of human pain (≈ 100 Pa) And yet the ...
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Room not getting cooled

I am in a room which is heated up duringg day, in night outside temp is quite low, but my room with a ceiling fan running still feels hot as it was in day if I step outside door its cold. There is ...
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What happens if I move air at relativistic speeds [closed]

What happens if I accelerate air to the speed of light? To be more specific I'd like to know what will happen if I do the following: some volume of air (just regular atmospheric air), I accelerate it ...
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1answer
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how to get high humidity and low temperature in room [closed]

I want to start mushroom farm for that I have to maintain high humidity and low temperature for that ,So i finding solution for how to get high humidity and low temperature at low cost.
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Can air make shadows?

I have read about schlieren photography which uses the ability of non-uniform air to create shadows. Is it really possible that air makes shadows?
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Why do the force get bigger as the angle of roof get bigger?

I am doing this experiment at school to find out how the surface area of roof and angle affect on the wind force applied on the roof. My results show that the force gets bigger as the angle and ...
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28 views

Enclosures & Air Flow

Imagine you have a box, initially fully sealed with an electronic component generating heat. You create a small hole at the bottom and a large hole at the top. What effect does this have on airflow ...
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1answer
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Pressure of air in a cup

If I have a 1.0m long cylindrical cup, and fill it up to $h$ = 0.5m with water, then the 0.5m of air above it will be at atmospheric pressure. But if I now place a perfect seal on the cylinder, and ...
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Can I create a car that powered by sound energy?

If I create a car that has an ideal loudspeaker (that can emit sound with any positive real number of amplitude) on car roof then loudspeaker emit very very loud sound (sound may be complex or be ...
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How much air does it take to lift the seeds? [closed]

I have a vessel with seed and water in side. The is a total of 6100 Lbs. and water is 523.6 Gals. the bulk density of the seed is 178 Lbs/CuFt. The water seed mix is expected to be 8' above the ...
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Thermodynamics question about space height and temperature

Little "discussion" happening at our brewery and I'm hoping to get it answered once and for all. We put in a walk in cooler. Some of us think that making the cooler 10' high will make the contents in ...
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1answer
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If methane is pumped into a room, how does it disperse?

So, if methane (natural gas) is slowly pumped into a room containing regular air, does the methane mix uniformly with the air as soon as it's pumped in (immediately expanding to fill it's container), ...
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buoyancy of compressed air as discussed in a previous thread [closed]

i was reading a previously locked thread about the compressed air from tires in the movie transporter three, and the writer asked if compressed air is heavier than regular and therefore does not float....
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Relation between Temperature and Pressure inside a bottle in a room?

I have an empty bottle with no cap in my room, so it is supposed to be filled with air. I made the air warm inside the bottle by dropping an igniting matchstick inside the bottle. Warm air will rise ...
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Concentration change after dehumidifier

Suppose I have an airflow with a methane concentration of $x$ ppm. An FTIR gas analyser is used to measure the concentration methane in the airflow. However, the FTIR is susceptible to water vapour, ...
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108 views

Is it easier to lift an object in air rather than in vacuum?

I was reading about why lifting an object in water is easier then in air. The explanation goes on the line that the water which was above the object will fall downward and sideways, taking the place ...
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If I'm using a compressor typically used for powering nail guns and other tools, why can't I make the air colder when I release it?

I've always been fascinated in learning how to make liquid air, and I learned that there is a branch called physical chemistry, which deals in the manufacturing of different chemicals. My question is, ...
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how to influence RH and air presure to resistance of air

For example higher RH (relative humidity of air) provide lower air electrical resistance. But how I can calculate with this relation? Moreover air pressure (between 1500 and 500 hpa) can influence ...
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Is it possible to retreive energy from the air displaced by a moving car?

Correct me if I'm wrong : When a car is moving it creates an over pressure on the front and a lower pressure on the back. So, from the point of view of the car, the air hitting the windshield has to ...
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How much less efficient is air flow through a rectangular duct compared to a round duct.

Ive got to run a flat piece of ducting from one location by the extract fan to the extract vent due to limited ceiling void height. The extract fan output is 150mm diameter (area 17671mm); Im ...
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1answer
26 views

Airfoil down force measurement

I have an airfoil connected to two supporting uprights, and each upright has a load cell to the front and to the back, between the bottom of the uprights and a test mount surface. From this system I ...
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2answers
68 views

Is the air we breathe ionized?

Is the air we breathe ionized? I am reading a book that says that the air we breathe is ionized but from what I have read so far, it is only the air in the upper atmosphere that is ionized.
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Air coming out of balloon

I have discovered recently that when we have a balloon in a room filled with air, with temperature $T_1$, and then this balloon gets a hole and air is let out, the temperature of the air that comes ...
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How does a heated object raise the air temperature around it?

When object is heated and the heat source is removed, how long does it take to cool down and how it does it change the air temperature around it. If We know the temperature of the heated object and ...
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Two-photon absorption fluorescence of air

I'm wondering if there are any major constituents of air which are capable of undergoing two-photon absorption and ultimately fluorescing in the visible spectrum. The original wavelengths of the ...