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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3answers
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The speed of air rising through a heated tube

I would like to get an explanations of an observed physical phenomena. When a metal tube is placed vertically and heated and the air inside rises, the speed of the air moving through the tube ...
0
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0answers
7 views

What technologies exists today that can reduce the effects of air pollution on individuals (eg. carbon capture)? [on hold]

I'm researching the matter of air pollution and I would like to know if there are any technologies that I might not be aware of (beside carbon capture and Sharps's plasma cluster) whose objective is ...
28
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5answers
4k views

Why don't things get destroyed by gas molecules flying around?

Gas molecules go at an insane velocity, and though they are miniscule, yet there is a LOT of them. Of course, because of all these molecules hurtling around, there is air pressure; yet if you envision ...
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0answers
20 views

Hot air particles

I have a question- albeit random one!. I recently visited a friends place who used a standard shovel from the shed as a tool for moving hot charcoals around a pizza oven. Unfortunately the shovel was ...
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3answers
248 views

Is fuelless aviation possible?

I've read the article Gravity powered aircraft flies with no fuel. This is making me confusion, as I can not discern if it is credible. Is it an hoax?
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1answer
30 views

Is it possible to send modulated ultrasound wave from underwater to air?

Is it possible to send modulated ultrasound wave from underwater to air? In case of radio frequency it is refraction loss at the surface between water and air. Is it something similar for ultrasound ...
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7answers
3k views

Drying clothes with the sun's heat, without any air

Will my wet clothes dry if I hang them under the sun, and if there is no air around the clothes? In other words, do I need both air and heat to dry wet clothes, or is heat alone (in the imagined ...
0
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0answers
38 views

Self-made air pump - What does it take to pump up a balloon?

We are building a simple altitude-controlled balloon (idea borrowed from Google Loons). As part of that, we need an air pump to inflate a balloon acting as ballast (which is called a Ballonet in ...
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1answer
45 views

Can sound frequency create more ideal conditions for fire?

You may have seen the recent story of a device that engineers claim can extinguish flames using sound frequency. An older article loosely explains the theory behind how this works: Sound travels ...
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1answer
39 views

Air nozzle outlet profile efficiency, concave/convex

I need to design a contracting nozzle for air. The application is quite simple, consider it like an hair dryer but the flow speed is even lower. So the Mach number is very low and the flow laminar. If ...
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1answer
54 views

What exactly is wind?

What is wind? I think it is kind of a vibration of air particles. If so, is it a longitudinal or a transverse wave? Or is it just a bunch of air particles being pushed? Smells disperse in wind so ...
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1answer
31 views

How would a huge ball of air look in space from outside and from inside?

If you replaced the Earth (except the atmosphere) with air and kept the pressure linear to the center (of the now non-existing Earth) while ignoring the effects this would have on gravity and leaving ...
2
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3answers
94 views

How can Denver offer Hot Air Balloon rides?

So the air density in Denver is 1.0 kg/m^3. And heated air has the density of 0.95 kg/m^3. So adding the weight of the basket and balloon I don't understand how a hot air balloon could get off the ...
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1answer
71 views

Why is my breath hot when i open my mouth all the way, but cold if I blow like a whistle? [duplicate]

I observed this as when I want to cool my soup I blow like a whistle and when I want to warm my hands I open my mouth more as my breath is warmer now.
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2answers
113 views

An equation to describe a process of heating one room using hotter air from another room

There are two rooms completly isolated from the outer world (a closed system, no heat losses). They are connected with each other through a ventilation tube. Temperature in room A is 32 degrees ...
2
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1answer
42 views

Why does hot air rise?

Why does hot air rise? I did an experiment: I made a model of hot air and cool air with marshmallows and toothpicks. The hot air had more volume than the cold air. Then, I weighed it. They both ...
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0answers
34 views

Why does opening the sun roof at high speeds cause the air pressure to change inside?

When I'm driving at fairly high speeds (80mph for example), I've noticed that opening / closing the sun roof causes the air pressure inside to shift significantly, a change that I feel clearly in my ...
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0answers
20 views

how much air pressure can be varied (in dapa) when an empty syringe's plunger is pulled in and out?

I'm new to the forums so please guide me appropriately if this is the wrong place to ask this question. When the syringe plunger is puller out ,a negative pressure is created at the nozzle....Isn't ...
0
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2answers
71 views

Relation between sound waves and air molecules

The following was written in my book When sound waves travel in air, air molecules do not move. When wind blows,air molecules move. This produces variation in velocity of sound waves. The first ...
23
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4answers
3k views

If air cannot conduct electricity, how can lightning happen?

If air cannot conduct electricity, how can lightning happen?
3
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1answer
221 views

How fast would an object have to move to create a vacuum behind it?

When an object moves, I assume that the air above it, instead of remaining at the same general height, is pulled downward as it is passed in order to fill the low-pressure area behind the object where ...
2
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1answer
106 views

Why I can't feel the difference of atmospheric pressure between a closed room and outside?

As far as I know atmospheric pressure is the result of the weight of earth's atmosphere. It has an approximate value of $10^5 Nm^{-2}$. Then why I can't feel it? My physics teacher told me that we are ...
3
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1answer
83 views

How does a hollow-point bullet move smoothly through the air, presenting a 'cup-shaped' nose instead of an actual sharp-point to the fluid?

Hollow-point rounds move smoothly through the air when presenting a 'hollow cup-shape' instead of a traditional 'sharp point' to the fluid air. Does this mean the air trapped, and at some assumed ...
3
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2answers
575 views

What air pressure is needed on mars, to have fluid water?

The atmospheric pressure on the Martian surface averages 600 pascals (0.087 psi), about 0.6% of Earth's mean sea level pressure. There is a lot of frozen ice on mars, but it can't melt, because of ...
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2answers
56 views

Different sized pneumatic Pistons [closed]

If two different sized pneumatic pistons have the same amount of air pressure, will they exert the same amount of force? If not, would a bigger or smaller piston have more force? And an explanation ...
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0answers
42 views

unknown stresses in double-layer glass window

I live in cold place where outside temperature drops to -20. Currently, we have -20 and on my window, which is doubled layer glass with trapped air in between, I found a "polarized stress spectrum" ...
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1answer
102 views

If I take a bottle of air into space, and open it, then close it and come back to earth and open it one last time, what would happen?

I was reading this post, but no one seem to go further as say what would happen if you brought the bottle back to Earth? Guess what another thing I'm wanting got know is, what would now be in the ...
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0answers
19 views

Loud, low-frequency “booming” sound in car [duplicate]

I drive a Scion XD, and I've noticed that whenever I drive at about 40mi/hr or so with just the back windows rolled down, I get a loud "booming" effect at roughly 10Hz. What causes this? I assume it ...
0
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4answers
100 views

Can the weight of a bird be measured, considering air friction? [duplicate]

Assume that a bird of mass 1.5 kg is held in a box at height 500m and this setup is placed on a weighing machine. Now, the bird starts to hover in the box pushing the air downwards, and is at a ...
2
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1answer
172 views

Why does air feel cooler when blown through a small hole and warm through a big one? (for example from a mouth) [duplicate]

I hope the question is clear enough and I'm sure that you can try this thing quite easily yourself. When I blow air from my mouth to my palm through a small opening, I feel cool in my palm, but its ...
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2answers
79 views

Why Does Air Hold More Water When the Air is Warmer?

I know that when the temperature of the air rises, the maximum amount of Water it can hold before the water condenses to water droplets increases. But why is this - has it got something to do with ...
0
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2answers
33 views

About using screw in air compression and air Engine [closed]

I want to use screw to build compressed air engine, as following image As I designed, this screw rotate in a tube My Question is: How successful this idea? Note: If this question not related to ...
0
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1answer
88 views

Simple air resistance experiment

I have a paper plate, and I'm taping paper streamers to it. I have 0, 1, 2, 3, and 4 streamers. I tried to place the streamers at places equidistant from the next. 2mm are attached to the plate and ...
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0answers
17 views

Particle Velocity and Air Velocity

Is the any relationship (equation) between particle velocity and air velocity? Is it possible to determine the air velocity from particle velocity?
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1answer
42 views

Air Presure and Air Velocity from speaker

How do I determine/calculate the air pressure emitted from a speaker ? And how to determine the velocity of air from the sound air pressure ?
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3answers
88 views

Would using a fan cause an air conditioning system to think it's cold?

Recently my office manager said this, after I requested a desk fan: ...using a fan causes a draught, which then leads the air conditioning to believe it’s cooler than it is and it then blows out ...
0
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3answers
61 views

How would filling a milk canister with helium affect the reading it makes on a scale?

Let's say that if I put a milk canister on a scale it shows 10kg. If I fill it with Helium it must necessarily be less than this, right? Can someone explain this (probably trivial) thing to me? :) ...
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3answers
2k views

Is it possible to make laser beams visible midair without smoke?

My question is: Is it possible to make laser beams viable midair without smoke? I thought it would be a great idea to have a (second) smartphone or pc screen without having a solid screen. The reason ...
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1answer
22 views

AIR PSI formula maybe

How would one figure out the maximum PSI (air only) a particular container may hold knowing only its dimensions? I understand the water formula. P=.434 x height I would like a formula for air ...
38
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6answers
3k views

How much air needs to be displaced to generate an audible sound?

I'm reading a book where in one scene a wizard/alchemist teleports a scroll after reading. He folded the parchment carefully and muttered a single cantrip. The note vanished with a small plop of ...
2
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2answers
113 views

Could one make steel balloons? [duplicate]

Reading this question reminded me of an idea I once had, and I wonder whether it's feasible. Imagine a hollow ball made of something strong, like steel. Imagine there is nothing inside; only vacuum. ...
22
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8answers
6k views

Is it possible to create a parachute large enough to stop all velocity?

This idea came to me while playing Kerbal Space Program. I noticed that the larger my parachute was, the slower my rocket would fall back down to Kerbin. I would like to know if it is possible to ...
1
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1answer
319 views

how does air pressure affect the speed of sound

How does air pressure affect the speed of sound in relation to its kinetic theory etc? I have tried searching this but i have not found a suitable answer as other websites simply related to air ...
1
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1answer
127 views

Different density objects falling on Earth's atmosphere?

So I finally understood why 2 objects with different masses, free falling from the same distance reach Earth's surface at the same time (due to the objects Inertia). Now when the objects fall in the ...
1
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1answer
29 views

Ostwald gas solubility for air-sea gas exchange of O2

The bubble-mediated component of the air-sea gas exchange can be parameterized with Woolf's (1997) formula as: $$ K_{b} = W \frac{2450}{\beta_{0} \left( 1 + \frac{1}{\left( ...
1
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3answers
168 views

Why do cold drinks get sweaty?

I drink a lot of iced tea and live in a very humid part of the country. My drink accumulates so much water, I had to purchase coasters to collect all the water dripping from the sides. Where does ...
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2answers
699 views

What will happen if a hairdryer is turned on in an air tight box?

I wanted to know what would happen if a hairdryer is turned on in an airtight box.
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3answers
882 views

The physics behind Balloons lifting objects?

Apologies for the super basic question, but we all have to start somewhere right? Can somebody please explain exactly how you would calculate the number of helium balloons it would take to lift an ...
2
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1answer
60 views

Effect of gravity on large tower with reduced air pressure

Suppose I built a 5km high building. The pressure of the air at the top would be around 50% compared to the pressure at the ground (I assume that the exact values don't matter in my case). Now ...
2
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0answers
109 views

Calculating PSI generated by water entraining air as it flows down a pipe

This is the concept used in a trompe. Basically, the idea is that if we allow water to flow down a pipe and if that pipe has inclined air intake orifices near the top where the water enters, then the ...