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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Does hot air have high pressure, and does compreesed air have high pressure?

I have hear a lot about high pressure. Sometimes it says that warm air is less dense and has low pressure, but I thought warm air has high pressure. I know that compressed air is going to be hot, so ...
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what is the degree of ionization of glow discharge tube air at various pressures?

From the minimum air pressure to the highest air pressure achievable with glow discharge tubes what is the degrees of ionization associated with them? What is the minimum degree of ionization of glow ...
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How to see wind?

Is there a wavelength of light at which you could see air moving? I was thinking it would be amazing to put on a pair of goggles which enables you to see how air moves around across a landscape, while ...
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What is a safe mass flow rate

In my machine class, the instructor said that if we use compressed air to clean metal of ourselves then we'll actually get hurt because the pressure is too high. I am wondering, What is considered a ...
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Can I make the water boil simply by spinning it in a glass?

Correct me if I'm wrong, I think the pressure in a fluid reduces when the speed increases(The airplane rises because the air above the airfoil moves faster than the air below it). Next, looking at ...
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Will helium in the tires of a bike make it lighter?

I know that helium balloons float because it is less dense than air. I'm not expecting my bike to float, although that would be pretty cool. I just wanna know if replacing normal air with helium in ...
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Does a fan's orientation with respect to gravity affect its flow rate or static pressure?

I just recently got a blower/centrifugal fan to use for layer cooling on my 3D printer and I'm thinking about how I want to mount it. My primary question is exactly as the question title says: does a ...
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Why does a skipping rope produce sound when going suffciently fast?

I was wondering how exactly sound waves are produced by a skipping rope. Specifically a plastic one, but I think it should occur in all materials. There are two possible explanations I can think of: ...
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583 views

Trajectory with air resistance angle to hit target

How do I calculate the angle required to hit a target, I found this at Wikipedia: http://en.wikipedia.org/wiki/Trajectory_of_a_projectile This works very well but my problem is, that in my case air ...
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Which balloon has the higher pressure and why?

I know that when two soap bubbles of different radii are connected by a tube then air will flow from the smaller bubble to the bigger bubble. This happens because the pressure inside the smaller ...
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Why do flat objects land softly?

I noticed that if you drop a flat surface, parallelly from a relatively low height, onto another, the impact is almost cushioned. What is happening here? Is this to do with the air, especially near ...
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Vibrating hot air around heater

The other day I was in a restaurant and I saw one of those patio heaters that looks like lamps turned on. The air around it appeared to be vibrating. Why does this happen from the optics point of view?...
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Can you power a car by using air pressure [closed]

In my fluid mechanics class, I've learned that a fluid traveling in a pipe will generate a force when the exit area is smaller then the entrance area. Suppose a pipe is attached to a car that will use ...
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How air gets filled in bicycle tire without removing its valve tube?

If I remove valve tube from tire, air inside the tire comes out. but we fill the tire with air pump without removing its valve tube. by doing this air gets filled it. How something going in with ...
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Air bubbles in boiling tea?

I read a few topics about forming air bubbles in boiling water,for exemple:tea. See: http://apho2011.tau.ac.il/.upload/APhO2008_theory_prob1.pdf Water is formed by hydrogen and oxygen. How can air ...
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does air pressure inside a ball affect its mass?

If we increase or decrease the internal pressure in a basketball for example, does that affect the weight or the mass of the ball? I am calculating the energy dissipated as the ball bounces having ...
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Venturi effect better for cooling through duct

I have a laptop which is overheating, and I would like to improve the cooling (without opening the laptop). The only option I can see (reasonably) is to increase the airflow moving through the laptop....
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How much air would be needed to block sunlight?

Was watching a sunset on the sea, I was wondering what would be a lower bound for the thickness of air needed to almost completely obscure the reddish light of the sun, or at least to make it ...
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Focusing electricity through air

Everyone knows there exist such things as a tesla coils. Those tesla coils have high voltage and since air conducts electricity bad, with high voltage it is still conducting it. My questions are: is ...
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Pressure from a tube into an airbag

I am working on an engineering problem, but need some physics thinking to get my head around it. I have a DC pump connected to one end of a slim tube. The other end of the tube is connected to a ...
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242 views

Brunt-Väisälä frequency

Just to be clear, I am not asking you to solve this problem. This is a homework problem, and all I am asking for is if there was a mistake in the question. The basic setup of the question is that a ...
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1answer
493 views

What prevents a humidifier tank from draining

I have a humidifier with a tank that drains downwards (towards the ground). The tank is air tight except for when a little plunger at the bottom is depressed, which opens a small (~1cm diameter) drain....
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why is gas(air) not used instead of liquid(water) in pumps like hydraulic pumps?

Given that Both gases and liquids can't be compressed less than their volumes like solids. I kinda know that bursting of compressed air is more devastating than that of water. But are there any ...
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Why is the air in high atmosphere typically colder than on the ground? [duplicate]

The air at 10.000m altitude is mostly a lot colder than at the ground. Even if you are in the desert in temperatures of 40 degrees Celsius, the air above you will be significantly colder (below 0 ...
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1answer
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What is the deflective efficiency of glass?

If I have ions, electrons, and gas particles bouncing off of glass, how much energy will the particles retain? what % of the energy will be be retained what % lost, the particles I am referring to are ...
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air molecules in space

Just wondering about escaped stuff in space like air and water molecules. Where would those molecules ultimately end up going? Considering that there is other gravitational forces in space like ...
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1answer
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What Causes Slanting Pointed Ice Spikes to Form? [duplicate]

Ice spikes are fairly rare but there is a general consensus about how they form from extruded pressurized water in containers subjected to below freezing conditions. This morning as I fed my dogs I ...
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How do moving colliding particles create heat? [duplicate]

I have a question? If moving colliding particles create heat then how come the cold wind is not hot but it has moving particals? Why and how do moving particles create heat? Just curios. Thank You ...
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Novel ways to gauge pressure

I'm interested in determining the pressure of a pipe filled with compressed air with some degree of accuracy (~10% of total value~) using systems that are not just a supplied pressure gauge. eg - one ...
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How does a hood keep my ears warmer while riding a bike?

This morning I was biking to my university downhill in ~$40^{\circ}F$ temperature. I was wearing a hoodie that resembles the one below (click for larger). Before I pulled my hood over my head, my ...
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How sound waves and the air work

I've come from trying to understand how Ethernet works to studying about waves. Question 1 So what I don't understand well is that the medium of waves return to their rest position or equilibrium ...
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How does the air flow behave when one puts fans in front of/beside each other?

If I have a single 120mm PC case fan which pushes X cubic feet per minute, will stacking several together proportionally multiply the CFM, velocity, and/or the pressure? If I put them in parallel, i.e....
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Thought Experiment: If you fell out of a plane at 36,000 ft (11km), would the additional air pressure from falling allow you to breathe?

Imagine you fell out of a plane at 36,000 ft (11km), roughly cruising altitude, with a parachute. If you deployed your parachute immediately, you would be stuck at high altitude with no oxygen, and ...
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Breathing with a bag on head [closed]

I got into an interesting argument after seeing a image of someone protecting themselves from splattering oil from a frying pan with a plastic bag over themselves. First question is: can a person ...
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Does a trumpet operate using an open air column or a closed air column

Just as the title states. I could not find a coherent answer online. Many thanks in advance
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What changes about a helium-filled balloon on the surface of the moon?

In terms of air pressure, I think that the pressure inside the balloon should be equal to the air pressure outside so that it does not burst. So how will a helium-filled balloon behave on the moon in ...
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How can I determinate the air flow coming out of a pressure tank?

I have a trouble with a simple question (I think). Well, if a have a tank full of compressible air at a pressure of for example 6 bar and a valve with a hole of 8 mm diameter, how can I know the ...
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Is it possible for a substance to be lighter than air in a liquid state? [duplicate]

Is there a substance while in a liquid state that will have a lower density than airs density while in a gas state.
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Is there a difference in the Helicopter power needed to stay on different altitudes?

I heard that what can make a helicopter go higher is the presence of "Air" to power its engine. Let's assume that the amount air would be exactly the same at different altitudes, would the power ...
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Why is it sometimes hard to open the jar?

The thing that all of us have experienced is about some stubborn jars! Does anyone know what's the reason?I think it might be related to air pressure but I don't know how to explain it! Edit: Right I ...
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Does air have gravitational mass?

Air has inertial mass, obviously, but can it be said to have gravitational mass? Clearly there is a asymmetrical relation between cold air and hot air on the axis going towards and away from the ...
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If I'm traveling at the same direction and speed of the wind, will I still hear and feel it?

Because riding a motorcycle, I didn't feel a difference when riding in different directions.
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Replacing '< x' by a defined value [closed]

I do have a dataset containing nearly a decade of particulate matter measurements. At the lower precision limit of the measuring instrument, there are values given like ...
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How to calculate the amount of psi needed to pull a 150lb object? [closed]

I am working on a project, and I wanted to know how to calculate the amount of psi I would need to apply to a wheel-like mechanism (Like in a pneumatic torque wrench) to be able to pull a 150lb object ...
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572 views

Pressure rating on a container underwater with hole and partly filled with air

If you have a container that has a hole in the bottom to allow water into it, and place it in the water so that it is partially filled with air, what would the pressure difference be between the ...
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Is this formula correct for calculating energy requried to heat up 510 m_3 of air from 0 to 20 degrees celcius?

I'd like to preface this by stating that I'm by no means a physicist or even a physics student, but recently a sibling of mine had a homework assignment in which they had to calculate the amount of ...
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How do i calculate the concentration of oxygen in humid air?

For a combustion engine, i have data which is measured at certain conditions, say 15C, 1013hPa, and 50% humidity. I need to correct this when the actual conditions change to stay accurate. It's quite ...
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Is speed of Hot air rising gravity dependent?

Would say a heated air rise twice as fast in 2G than in the environment with standard Earth gravity?
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Do soundwaves produce heat?

Sound dies down after a while. The energy emmited by the speakers must go somewhere. Where does it dissipate this energy? Is it in heat? Theoretically, if i play music in a room, would it get hotter ...
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Is there an ideal proportion for water to air in an espresso machine?

Let's imagine a very simplified espresso machine, and let's ignore the pump etc. and focus simply on the boiler. This is a metallic cylinder containing water, with a heater at the bottom, and a pipe ...

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