Air Definition and 1000 Threads

The air parcel expands as it rises and this expansion, or work, causes the temperature of the air parcel to decrease. Imagine that parcels of _dry air_ go up inside the pipe that goes vertically from 0 to 5000 meters. Suppose that they go up because they are slightly warmer that the air...

Related to an engineering project I will be working on. The situation is that essentially I will have a closed cylinder (5.5 in x 26 in) with a small 15mm hole on the side (not on a circular face), which allows the air inside to be at equilibrium pressure/temperature with the outside. Then a...

Homework Statement We want to calculate the rate of air loss from a space vehicle (module) if a meteoroid punches a hole in it. Assume the module is sealed off from other modules. It is shaped like a cylinder roughly 4 m in diameter and 10 m long. The hole's area is a cm2. The hole is punched...

Hi, Could someone please help me in understanding how the air is thrust rearward by a propeller? I am specifically interested in how an axial-flow compressor, which uses aerofoil shaped blades to force the air through the engine does so, however I feel a good start is a propeller. It makes...

I am struggling with what seemed to be a simple problem and any help would be greatly appreciated. I have to determine the amount of pressure created when air is displaced buy gasoline flowing into a tank. The gas enters the tank at 10gpm. The entrance has a diameter of 1.5" and the vent has a...

Homework Statement An inflated tyre suddenly bursts. As a result of this the temperature of air (a)increases (b) decreases (c) may increase or decrease (d) remains constant. Homework EquationsThe Attempt at a Solution The answer in the book is (D) remain constant. Does it mean air outside the...

We have two identical balls sitting at the same height. One of them is released without applying any force (it falls freely) and the other one is given a non-zero horizontal velocity. Which of them will hit the ground first? The force of air resistance is proportional to the square of the...

Let's say that we have a bicycle wheel with radius $R = 25 cm$ and mass $m = 1 kg$. We spin the wheel in air so, that the tread is moving at the speed of $v_o = 50 km / h$. Then, we let it roll on asphalt, given the coefficient of static friction: $f_s = 0.9$ and kinetic friction: $f_k = 0.7$...

I've done the math but because i can't find this answer anywhere in the book which I'm reading and on the web, I would like to be sure if my calculations are correct. I know that if two objects (starting at the same time) are free falling without a drag force being applied to them, the...

Homework Statement consider a toroidal electromagnet with an iron ring threaded through the turns of wire. The ring is not complete and has a narrow parallel-sided air gap of thickness d. The iron has a constant magnetization of magnitude M in the azimuthal direction. Use Ampere's law in terms...

I saw on a web page a video of tiny Agnes Scott College vs Princeton University from 1966 on GE College Bowl.Agnes Scott won (!), but one of the questions that both schools got wrong was asked by the moderator: The speed of sound in air is about 1,100 feet/sec. The speed of sound in steel is...

Hi everyone I'm new around here and I wonder if anyone can help please. I'm taking hot air off the chimney stack inside a factory at a temperature ranging between 700 and 400 degrees going through a 4 inch stainless steel pipe with 3mm wall thickness. This pipe line will be about 35 meters long...

hi all, 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 image: i have sketched a small setup before i begin; the test will send a projected...

Hey everyone,I am trying to make a helicopter using an AVR or ARDUINO BOARD I wanted to know how do I calculate the force required to lift the helicopter.Can anyone also help me how much revolutions per minute(r.p.m) should the fans generate.I am planning to use two fans.

Homework Statement A car tire has a volume of 10 L and is inflated to a gauge pressure of 30 psi (207,000 Pa) at 20°C. How many air molecules are there inside the tire?Homework Equations N = PV/ kbT The Attempt at a Solution (207,000 Pa )x (0.01 m3) / (1.38 x 10^-21 x 293) =5.12 x 10^23...

I would like to know how exactly or if the velocity of air molecules affect the light i.e electromagnetic waves passing through it. Ignoring the effect of pressure and/or temperature differences in the air which might also affect the light (due to changes in refractive index).

Hey, everyone I just bought an air purifier yesterday (the Honeywell 50250 model) and have a question about whether or not it's normal what is happening when I turn it on. I followed the instructions exactly in terms of assembly (it was really only putting on the pre-filter - no other assembly...

Can someone explain why air rises to the highest point in the body cavities like peritoneal/pleural?

My wife and some of my friends have been experiencing a spike in moderate allergy symptoms (Sx) this past week or two, and I was wondering if adding a HEPA air purifier at home in our bedroom would help. This recent PF thread discussed air purifiers, but not really from an allergy perspective...

Hello all, I want to say thank you in advance for any and all advice on my question. My classical mechanics textbook (Marion Thornton) has been taking me through motion for a particle with retarding forces. The example it keeps giving is: m dv/dt = -kmv which can be solved for: v = v0e-kt...

Yes compressing air increase its temperature but does that necessarily increase pressure? In an pellet gun a spring driven piston compresses the air which increases the temperature but wouldn't any increasing pressure simply retard the piston's advance? Because the chamber volume is not fixed...

Hi, I'm an instructor at an online school, and my text says “ Air pressure is the amount of pressure the atmosphere places on the surface of Earth. Air pressure is usually measured as the weight of the column of air above a square meter (N/m2). As altitude increases, air density decreases and...

Looking to do a experiment on the effects of air resistance training on the body. doing basic exercises such as jogging push ups. Maybe a couple of curls ;).got facility design herewondering what your thoughts and opinions on this would be.

I"ve seen several texts that say something like this: Our equation of motion along x is dvx/dt = -g(vx/vt) Integrating this, we obtain equation 178 at this link (pretty near the top; sorry, but I can't figure out how to put the equation here). It's from FitzPatrick's online notes for...

Homework Statement Air consists of approximately 78% Nitrogen in volume, 21% Oxygen and 1% Argon. The atomic weight of Nitrogen is approximately 14, that of Oxygen 16, and that of Argon 40. Nitrogen occupies air in weight by (1) (a) 76% (b) 77% (c)78% (d)79% Homework EquationsThe...

A large tank filled with air is compressed to 49 PSI. A valve is open and air escapes through the hole (d = 0.04 ft) to the atmosphere. How long will it take for the compressed air to reach 29 PSI. Assume constant temperature. Not exactly sure how to approach this problem since the flow rate...

I had a helium balloon in my car tied so it hangs down by string toughing nothing. Windows are rolled up. Heat and AC are off. Air inside the car is not moving and car is parked with motor running. When I step on the gas pedal and car takes off forward balloon goes forward towards the...

The air conditioner is set up to put the temperature at 72F. Which I hate because that's cold, but whatever. The air conditioner turns on and works for about 6 minutes when it automatically turns off because the temperature reached 72F. It stays off for 10 minutes and then it turns on again...

If a pulse of light, which has momentum p = E/c, interacts with particles of air, would it not change their momentum over time, causing mechanical energy (sound)? As I understand it, sound is mechanical energy moving through particles as they vibrate. Why can't the momentum of a pulse of light...

I would like to receive some input about this "equation" formulated by me, a=f(i), regarding a system with a permanent magnet and an air core coil acting as an electromagnet, as described in the image: I understand that the acceleration provided to the toy car will be a function of the...

Homework Statement Air is drawn into a compressor at normal temperature and pressure (NTP) and compressed to a pressure of 6 bar gauge. After compression the air is delivered at 1.2m^3/min and cooled to a temperature of 30C, at which point condensate is collected at the rate of 2 litres per...

Hello, I am currently doing research on the aerodynamic properties of a rotating cylinder in a cylindrical housing. The cylinder represents a rotor in a electric motor. The air gap between rotor and stator is about 0.5mm. I'm looking for a theoretical analysis and calculation on the...

Homework Statement We are using a device(as shown in the image) to blow air into a 200L plastic barrel. We want to know how much air (volume) that is needed to raise the anchor from the seabed. Homework EquationsThe Attempt at a Solution The anchor will start moving upwards when the sum of...

So I'm trying to figure out what kind of energy that I can expect out of a few different setups. Here are the barrel bore diameters. .224 .308 .5 .77 The barrels are usually rifles and some projectiles are full size (size of bore) while others use sabot's where a .224 or .308 can be shot...

I've had some mold in my shower and even my car this past year (long story, but I HIGHLY suspect my car mechanic caused it, by leaving a nasty greasy residue on my fibers...). I also have allergies and eczema. :frown: They causes itchy rashes (though usually very manageable by avoiding...

Homework Statement Air consists of a approximately 78% Nitrogen in volume,21% Oxygen and 1% Argon. The atomic weight of Nitrogen is 14, that of Oxygen 16 and that of Argon 40 (1) Nitrogen occupies air in weight by (a) 76% (b) 77% (c) 78% (d) 79% Homework EquationsThe Attempt at a Solution I...

mass of air X velocity = mass of man x gravity (10000)x(v)=60x10 velocity=600/10000 how come velocity is so less? I am still in school so forgive me if my calculations look stupid.

How do I find out gauss from air core inductor 36mohm pumped with ~130amps 9ms long? http://www.parts-express.com/erse-25mh-14-awg-perfect-layer-inductor-crossover-coil--266-380 Greatly appriciated.

I'm looking to see how much the dielectric constant of air will change mostly as a function or air temperature. Is there a formula that outputs air dielectric as a function of temperature or atmospheric pressure?

I have noted three different phenomena due to high electric fields in air. 1. When I run a ten-stage voltage multiplier I get sparking and crackling. 2. When I run the multiplier but current limit the output with ten 720k resistors in series, I get a violet arc that is sometimes smooth and...

Recently, the inverter ACs have become quite famous. I got to know that in inverter ACs, the compressor is never actually switched off. The compressor speed is varied in accordance with the temperature of the room. This keeps the room temperature constant, unlike the previous technologies, where...

Hi, I have a airbottle of 30bar pressure, 1000lit.From the airbottle I had made a line of 25 nb and fitted a pressure reducing valve in the line with set pressure 5bar.I am interested to know the flowrate in the line. Please help

I am a contractor. I install water lines. Once installed we have to pressure test them. We pump the lines up to 150 PSI of water. If the PSI drops one of 2 things is wrong, either i have a leak in the line, or there is a small amount of air in the line. Generally if it is air, it stabilizes...

Homework Statement From a previous post in this forum, unfortunately the thread is closed for answers otherwise I would have posted it there: https://www.physicsforums.com/threads/thermodynamic-filling-of-tank-matlab.479112/ A 70 ft3 rigid insulated tank contains air at 14.7 psia and 80 º F...

Hi, I have a question about air flow. My room is located on the corner-end of my building, on the 7th floor. I have two windows, each one facing a different side of the building, and one of the windows typically produces the breeze, and the other never does. When the door to my room is closed...

Hey guys! Can anyone tell me how to calculate the force of air friction on meteor that's going to impact

How a helicopter can stand still in the air?

Wondering if I have a sealed steel tank filled with air and the air temp is 0C and the air pressure in the tank is 0, then heat is applied to the tank - what will the pressure be 100C? At 200C? At 300C? I assume the rate of expansion is constant, but correct me if this is wrong. Thanks.

Homework Statement An EM wave from air enters a medium. The electric fields are --> ^ E1 = E01 cos(2πv(z/c-t) x --> ^ E2 =E02cos(k(2z-ct)x in a medium ,where the wave number k and frequency v refer to their value in air.the medium...

Hello, I don't know how to compute that number, but probably is a kind of reference value... Q: How many ion-pairs are there in normal conditions* in the air? (This is not homework, it is just out of curiosity.) Thank you for your time. Regards, ORF * 1 atm, 300K.