Air Definition and 1000 Threads

After a big mistake in this PF, I try to post my question here, hoping it is ok. I'm looking for a more "simple" relation than Darcy's law. I try to determinate what is the relation between air speed and differential pressure in a tube where there is a restrictor. A kind of relation like V=kP...

Hello everyone! I was thinking about how to reduce air drag for a vehicle so that one gets better mileage. Here is the definition of the problem: A moving car faces air drag especially at high speed. The resistance of the air layers would try to slow down the car. In order to maintain the same...

I am working on a model for predicting cooling in a system that evacuates a vessel and cools by evaporation of water and the water vapor is condensed in a tube and shell heat exchanger. My concern is the prediction of the steam side heat transfer coefficient as the air is removed from the...

I'm just trying to think of a qualititive solution to the following thought experiment: I have an RF source of very large voltage driving a signal towards point A (say, a capacitor or a dipole antenna). The source itself is not really part of this experiment, but I just want a sinusoidal...

Is air resistance dependent on mass? thanks!

Let's say you have a small metal case that is 3 inches by 3 inches versus 2 inches by 2 inches. Inside at center is a heat generating source (let's say a small processor chip). How efficient is the transfer of heat from the processor to the air... and from air to metal between the 2 different...

Sorry if this is the wrong forum to ask. I have a fine spray application where I need ~140 psi but only .3CFM. I'm trying not to buy a regular air compressor (money wasted on unneeded CFM) and am looking at tire inflators, but very few of them have CFM ratings. Any suggestions?

Let's say I have a cold bottle of water in a warm room (temperature is constant). Is it possible to calculate how long it will take for the water to reach a certain temperature? Do you guys know any formula for this? To be more general: What is the effect (W, J/s) that air in a certain...

Hello everybody, I have a new thread to post,it is very important to find a solution for this : -Imagine a box full of air particles.The particles are forced to move to a point A on the edge of the box.My question is now,how can I mathematicly describe the movement of these particles toward...

Is it possible to reflect light off of air? If so, what would it look like?

Homework Statement A bucket with surface A, full of water, is pulled upwards through humid air, humidity ρ[mass/unit volume], at constant speed v0. the cloud is at rest and the drops instantly stop at hitting the water. Homework Equations Newton's second law: ##F=\frac{d(ma)}{dt}=\dot m...

I am very curious about holograms and if there is a possible way to project 3D , mid-air images and videos on air with no holographic screen (The Princess Leia hologram in Star Wars). If it is not possible, how long till they actually start arriving to the world and how will they work/operate?

I'm trying to solve this ecuation: Y_1=(-m)/2k((T-mg-kv^2)/(T-mg)) I'm having some truble at finding a correct formula to find the air resistance. In my research through Internet I found loads of different formulas but I don't exactly know which is the correct one. In an other discussion on this...

Hey everyone... so I understand that an alpha particle, being a helium nucleus, is quite a large particle compared to, for example, a beta particle. Due to this, it will encounter a lot more collisions and impart its momentum to other particles of air at a much more rapid rate. Is there...

Is there a solid that has a density of or below the density of air or any gas?

Hi, I'm trying to understand vortex shedding and how the Karman vortex street occurs when air flows around a cylindrical object, so far it's going OK but then I came across this part of the explanation which leaves me confused: "Looking at the figure above, the formation of the separation...

If a furnace at 500 Celcius and 500 bar was to lose pressure from a breach (pipe break) resulting inert gas escaping the furnace would loose pressure and reach equilibrium pressure with outside room pressure. When equilibrium pressure is reached how would the outside air enter into the...

I recently read that the impact of air resistance on the horizontal range increases as the launch angle increases (http://moodle.davidson.edu/moodle2/pluginfile.php/121168/mod_resource/content/2/Brancozio%20fly-ball%20paper.pdf). A graph depicting this is attached. Is there a reason for why this...

we know that air pressure on our Earth is 1 atm. Also 1 atm = 10^5 P Also we know Pressure(P) equation = P = F/A So, F = P*A So if small area(A) in which we are standing is also taken then pressure force is that area(A) times 10^5(Atmospheric pressure in Pascal) i.e 10^5*A So why don't we...

Hello, My GCSE class just did a practical investigation into how the width of a Bunsen's air hole affects the temperature change of a beaker of water. The entire class found as expected that the size of the temperature change increased as the hole was opened further, but they all found that...

If you have, say, two tubes of different internal pressures submerged to a given depth (for sake of the example, let's just say 1,000M underwater or 100 ATM), will the smaller internal air pressure tube experience a greater relative force from the water pressure? The water pressure on both tubes...

When we calculate the natural frequency of an open-ended air column, is the natural frequency we calculated pertaining to the air column or the hollowed cylinder containing the air column? I imagine that the natural frequency belongs to the hollowed cylinder, for the natural frequency of...

Of the few occasions I've seen Airfoil Lift described to general audience (on documentaries), it has focused on the top-side curve of the Airfoil causing air on the topside to move faster than the bottom-side. This is said to reduce air pressure on the topside and result in lift. If a wave is...

Hi Friends! Here is my query : I have two source of air supply with different pressures, temperatures and with different mass flow rates. Input 1: P1,T1,m1. Input 2:P2,T2,m2. Output: P3,T3,m3. P,T and m refers to pressure, temperature and mass flow rate respectively. If the mixing is being done...

When a loudspeaker moves back and forth, sound is generated. The moving of the loudspeaker diaphragm causes condensation of air when it moves outward, and rarefaction of air when it moves inward. When this movement is happening at a certain frequency, we hear a sound. See for example this...

Hi, My company builds machinery with multi-zone hot air dryers. Each dryer has 2-3 supply blowers that push air through an electric heater and then through a duct into a plenum (one plenum for each dryer zone) at the top of the dryer. Each plenum is fitted with multiple air nozzles that...

I hope this isn't too simple for this site. I have had a challenge at work trying to eliminate air bubbles from a paste in a 20oz cartridge. The cartridge has a piston in one end to push the material out and the other end tapers to a small threaded 3/8" opening. I won't take the time explain...

So I'm looking for how tall I could make a tower of concrete, using any reinforcments, in an environment of only gravity starting at sea level. Could it get so tall it'll own gravity would effect it, the moons, or the sun's gravity, or would the bottom give out will before that?

Homework Statement A capacitor is charged to V = 5 kV. A wire is then connected to one plate and is slowly connected to the other. Before actually touching the plate, a spark of length l = 1 cm shoots from the wire to the plate. Using this information, estimate the dielectric breakdown of air...

I posted this on Eng-tips and no replies yet:( I'm trying to design an as-simple-and-cheap-as-possible supersonic wind tunnel using an air compressor (this even possible? given the energy losses from shock waves...). I have access to a Porter-Cable 150psi, .8hp air compressor. Questions: 1...

Can we apply Euler's Equation and continuity equation to compressed air flow from tank or orifice.

Hi all. I'm trying to find haw much energy is required to get the air heated up to one desire temperature in oven. . I guess the next issue will be haw much energy is required to keep the temperature at the setting point. A theoretic starting point will be useful from your side, if possible...

Hey guys, i am new to this subject and need some help. The idea is that in area AxB there is a constant airspeed of for example 6 m/s. I would like a formula or another way I can calculate the airspeed at area ExB. I hope you guys can help me out. Thanks. If image is not visible it is on ...

Unlike firearm projectiles, air rifle pellets have evolved to a generally typical diabolo configuration. For reference, see: http://www.photosbykev.com/wordpress/2009/01/20/air-rifle-pellet-database/ The initial shape was described as like that of a badminton shuttlecock, and "skirt" at the...

http://www.stuff.co.nz/world/europe/68883327/danish-radio-station-defends-killing-baby-rabbit-live-on-air I'm totally disgusted. I will be investigating the Danish laws around animal abuse, and seeing whether this constitutes a breach of law.

Homework Statement This is a standard projectile motion problem, the mass is m, the drag is F_r = - alpha *v, where alpha is a positive retarding coefficient. The origin is the ground and at time t = 0 the horizontal and vertical velocities are positive a) Write down Newton's second law for...

Homework Statement A car rubber has the volume 50 liters when it is bloated in a pressur 1.8 atm and in a temperature 293 K. After some hours of journey as an effect of friction the pressure will become 2atm. Find the change of internal energy of the air inside the rubber (U) Homework...

Hi all, I have what I believe is a simple physics question. I was burning a sprig of incense in my apartment, and noticed that the smoke was rising from the burning section perfectly straight up into the air for a good meter, and then started to dissipate into the air. I know that a gas will...

I have been trying to control the water level in a water hole that I have using a siphon system. I have a 1.5 inch hose that is submersed in the upper water hole and the hose travels slightly up hill for a 100 feet then goes slightly down hill for the other 100 feet into a large barrel of water...

I actually have 2 questions that I am getting stuck on around the same point.. Question 1) An arrow with a mass of 80g is fired at an angle of 30 degrees to the horizontal. It strikes a target located 5 m above the firing point and impacts the target traveling at a speed of 20 meters/sec. If...

I'm working in an engineering internship after my first year and we haven't covered fluid dynamics in my program yet. I've been assigned to find flow rates and velocities in several branches of a suction (dust collection) system in our factory. The main branch has a diameter of 30" and is...

Hello all! Can you please provide some guidance with this problem? 1. Homework Statement Calculate the air pressure at 3000m above sea level assuming that the molecular weight of air is 29 and the ambient temperature is constant against height. Homework Equations Stokes-Einstein equation. In...

Let's say i have an air pump which produce plenty of air flow, but almost no pressure. Is there a simple way to turn this high flow, low pressure into high pressure, low flow? I'm thinking something akin to a gearbox turning fast spin, low torque of a motor into a high torque, slow spin output...

When you are driving and open the window, wind blows into it, but what causes the perpendicular direction of the air's motion to your direction of travel into the car? For instance, a bus. A bus is basically a rectangular prism with parallel window sets on either side, completely parallel to...

I bought a new home AC (split; 1.5 ton) and the tech the company sent to install it didn't seem to have neither a vacuum pump nor a N2 cylinder in his kit. I am leery. Is it really possible to install an AC without these items? Can he do a reasonable job evacuating the lines & leak testing any...

Hello I am trying to design a vacuum using venturi. I cannot quite get the air flow created by the rotation of the fan, which is connected to the engine. How is the relation between the fan speed and the flow rate created by it? I know the proportionalities between the speed, power and the...

It would seem to me that if you fly from point a to point b following the rotation of the earth, you'd have to go faster than this rotation to move forward. For example, if the Earth spins at 1,040/mph, then wouldn't a plane have to go faster than this just to escape the spin of the earth? I get...

I am currently trying to use a centrifugal fan to force air through a small tube however i am looking for some information on how to better the design and performance as what i have currently is severely lack-lustre. This is just a prototype for controlling rate of airflow and all i had on...

How we can incorporate valve lift and variable flow rate in compressed air engine Mechanical power = air power torque * angular velocity = pressure * flow rate

Hello, I have a cart going down an air track with an inclination of 7 ° and for some reason my acceleration is going on a downward trend, my velocity is increasing and naturally so is the time. to find velocity I'm using v = (2x)/t and for acceleration I'm using a = (2x) / (t^2). Can you tell mr...