Air Definition and 1000 Threads

Evaporative cooling is pretty cold, but I wonder how effective the following would be at chilling the air even further, even if not very energy efficient with having to freeze ice, additional air pump, etc. I was thinking that since the air in the air chamber was cooled, the ice would melt at a...

Homework Statement Hello everybody! One surface of a biconvex lens (n=1,5) is in the air (na=1) while the other surface is dipped in the water (nw=4/3). If the power of the lens in the air is Po=10 Dioptri, The lens power in such condition is? Homework Equations Lensmaker Equation...

Alright It's been over a year since I've posted and received amazing help the last time I did. Now I've a question I cannot seem to find an answer to. Say you have an electrical charge and use a transformer to step up the voltage high enough to where it arcs in air. Then you have a conductive...

Hello, I'm having a question regarding the sensors and the techniques in fluid mechanics. Since my skills are amazing in this field, here I'm asking you questions xD I want to measure the air pressure of this tube/pipe (P1,P2,P3). This pipe will be flushed with water and then with compressed...

Hi i would to know how to predict the air quantity need to blow up a definite-shaped object, like a tyre, to a certain pressure. i would to apply the ideal gas law, i should obtain something like P/m=cost. is it correct? i supposed temperature and volume constant

Homework Statement Let's have a cylinder in air tunnel. The air is flowing around cylinder. I want to calculate a net force acting on the cylinder. Part of the incoming air hits the cylinder and its trajectory direction changes. For that reason we can see straight behind the cylinder lower...

As a follow-on to this thread, which in turn followed this closed thread, I'm starting a new thread on a related real-world problem. Say I have a 2-liter plastic soda bottle filled partway with water, and pressurized. It has been sitting inverted (with the opening pointed down, and sealed) for...

Hello everyone! Summer is coming and instead of buying a $200-$400 air conditioner, I'd figure I could try a DIY version. I came up with a schematic (attached below) and how I think it would work. I feel like I'm missing something blatantly obvious that will make it not feasible. Wondering if...

Good evening, Today's planes' need bleed air to start. Above a certain speed, igniters fire up and we inject fuel inside the combustor chamber. Why do we need to have the engine running to inject fuel (around 20%N2)? Can we simply not inject fuel with static air (i.e. when engine is not...

Hi people. Here the situation. Balloon filled with air I throw in the air. Balloon starts to move upstairs. It slows down and then is starts to fall down to the Earth. I'm interesting only in the movement of upstairs. Here the picture. In the first case (left) I choose the direction of...

Homework Statement (Simplified) During tests at cliffside power station, the following data was recorded from the cooling tower. A cooling tower has a 9 cell draft design, each diameter is 10m. Data D_o = 10m V_exit = 14.4 m/s T_exit(15 celsius) = 288.15K Ambient conditions : T(15 celsius) =...

I am a student of electrical engineering. This task appears in our textbook. However, there were no solutions provided. I tried understanding the task but got lost in the process. This is why I seek help here on this site. I would like to ask you for guidance and any sort of advice on how to...

If you have an non-viscous incompressible fluid flowing in a pipe whose static pressure is higher than atmospheric pressure, then after exits the pipe will the dynamic pressure increase? The static pressure of the fluid right after exiting should decrease because it should be equal to the...

Homework Statement A tank with a 25.5 litre capacity contains air compressed into 355 atmospheres used to drive a torpedo by expansion into an engine via a pipe of diameter 0.08cm. A mechanism ensures that the gas flows to the engine at a constant rate and any cooling of the air during...

Homework Statement A spring toy is launched from the ground at 2.3 m/s at an angle of 78° to the ground. What is the maximum height reached by the spring toy? Homework Equations ## \vec v_1v = \vec v_1 sin\Theta## ## \Delta \vec d = \vec v_1v \Delta t + \frac 1 2 \vec a \Delta t^2## The...

Homework Statement A horizontal stream of air is blown just above the open end of the hares apparatus with an initial speed "V". The density of air is 1.2 kgm-3.Then the water column rises to 6 cm in the respective limb.Density of water is 103 kgm-3 Using Bernoulli`s principle find "V"...

Homework Statement -[/B] What is the weight of air on a piece of 8 1/2" x 11" piece of paper? Assume you're at sea level. Homework Equations [/B] None.The Attempt at a Solution All I know is atmospheric pressure is 14.7 lb/in2 at sea level. I have no idea how to go about calculating this...

What i mean is how much force would a person let's say 160lbs have to kick the air it be propelled upwards? This is all based around the double jump idea from games... Air is a gas and gases have resistance so it makes scene if you could put enough force into a spot you should be able to be...

Are there any good research papers or established theories on using skis with either porous air bearings or an air skirt with holes to send pressurized air out? One of my concerns right now is the stability of a ski (ie any particular shape each ski/section should be and whether we should divide...

Per cubic foot of hot 90F humid 80%RH air, how much water is released when that air temp is dropped to 40F? Thank you for any comments.

Hi all! I have an optical system made up like this: Circular led source -> smaller circular diaphragm -> circular even smaller lens -> cmos sensor at the posterior focal plane This is the in scale model: The image is optically after the focal plane, but practically it will lie on it due to...

If air drag is a factor, how will it affect a projectile’s trajectory qualitatively? Its velocity? Its acceleration?

can cold air become water in a vacuum cylinder?

Homework Statement Two rocks are thrown off a cliff at the same initial speed, v. The first rock is launched at an angle, ϴ, directed below the horizontal. The second rock is launched above the horizontal at the same angle. If air resistance is negligible, the rocks would hit the ground at the...

I 90% understand the question and solution but unfortunately I have some hesitations about the formal solution in the book. First of all, when calculating P4-P3, choosing lines and points on them, why do book assume velocities of 3 and 4 to be the same...

Morning all, I am working on a Air Cannon Project and have hit a stumbling block. I am trying to work out what tank pressure and volume I would need to project a 1.4kg mass to 83m/s when it leaves the barrel. The barrel the mass will travel down is 4 meters long and 6inch in diameter, would...

looking at where to start understanding how the thrust/lift generated by a specific propeller (hypothetical one) changes as a function of surrounding air pressure. obviously the lift will go to zero as air pressure decreases. as pressure increases, modeled by say mounting the propeller inside...

I'm confused on why the dry air gas constant varies: Dry Air Gas Constant of 286.9 from The Engineering Toolbox Dry Air Gas Constant of 287.22 from https://www.physicsforums.com/ttp://www.peacesoftware.de/einigewerte/luft_e.html Dry Air Gas Constant of 287.05 from Brisbane Hot Air Ballooning...

I was not sure where to post this so decided to start here. If there is a better section please let me know... If you put a sealed device on a scale and place in an air tight box then fill with air pressure would the weight change of the device if there was a leak? I am trying to do a test to...

I was not sure where to post this so decided to start here. If there is a better section please let me know... If you put a sealed device on a scale and place in an air tight box then fill with air pressure would the weight change of the device if there was a leak? I am trying to do a test to...

Where can I found values of the relative permittivity of air at different temperatures, frequencies, pressure, humidity, etc. or its dependence? I'm particularly interested in data around 1.4 GHz, 25ºC, 1 atm. 50% hum. Thanks in advance.

I have a centrifugal pump 50 m above a vessel, I’m pumping water in at 4 bar gauge into this vessel. I then close a valve to cease pumping ensuring no air enters the system.My question is, if I now open that same valve to atmospheric air this time, will the water exit from the pipe through the...

If air resistance increases with velocity, then if a ball is thrown upwards, does air resistance decrease as the upward velocity of the ball decreases or does it only increase and remains constant when the upward velocity of the ball decreases?

It is usually referred to as Phonons for sound waves in solid. But, where it gets confusing, is in gases and air. Some still call it Phonons, others say, Phonons can only be used in solid states. So what is the Quantum of Sound in Gases/Air? And if possible, refer to any text which speaks of...

Currently I am an undergraduate physics and mathematics double major. I am looking into the air force after graduation because I heard there are a lot of opportunities for people with STEM degrees but I have no idea what kind of opportunities are available for my degree paths. Joining the Air...

Homework Statement So in the problem there is a projectile that is in the air and has no forces acting up, only the -9.8 acceleration down, the projectile is at the maximum height of say 10m and at this height (with a horizontal acceleration of around 40 m/s) explodes into two even 20g pieces...

Hi all, Not sure it's the right place to ask but I found these while walking on the beach, they seemed to have come from the sea. They "explode" if you walk on them. Any ideas what this could be? https://ibb.co/fuL0gF https://ibb.co/ikrUaa https://ibb.co/hj3LgF Thanks, Audry

Homework Statement The door of a refrigerator is 1.5 m high, 0.80 m wide and 6.0 cm thick. Its thermal conductivity is 0.21Wm-1 degrees Celsius-1. a) what is the heat loss per hour through the door neglecting convection effects? b) Air is usually still inside the refrigerator so there will be a...

I have a tube 40' long by 8" internal diameter, sealed at one end. Assuming an ideal plunger is inserted into the open end, how much force would be required to compress the air (starting at 1 atm) from 40' (1005 ft/cu) to 36' (904 ft/cu)? Any hints as to the calculation required for this would...

I'm a mechanic who is currently doing a study automotive engineering. Being someone who worked on both diesel and petrol cars I know what a higher or lower air fuel ratio (AFR) will do for both engines. However I don't fully understand how the following is possible. "Adding fuel in a diesel...

I’m looking for material capable to act as filament of thermionic emitter in open air. Classical tungsten filament is not capable, because it readily oxidizes. We experimented with filaments made from SiC and ZrO2 (Yttria stabilized). At 1900K SiC provides certain degree of emission, but it is...

What do you think about conditioning the outdoor air? Is it impossible? Is it useless? Is there any research about it?

I am a software engineer. I am working on an experimental project to attempt to measure in real time the variation in air pressure (relative to the ambient pressure of the room) in a piston style apparatus. In this model, I am expectant that there will be a measureable change in the internal...

Not really sure what's happening here, did a short search online to see if anyone else has documented this before. (If it's not clear from the photo, there seems to be a air bubble trapped right under the stream) It sustained itself for a couple minutes, took a short video of it too before it...

Homework Statement You come across a dead body at 3 PM. Its temperature is 83.6 F. 30 minutes later its temperature is 78.6 F. How long was the guy dead before you found him? Homework Equations ##\frac{dT}{dt}=-k(T-Tair)## T(0) = 83.6 F T(0.5) = 78.6 F The Attempt at a Solution This is a...

Hello, thanks to everyone who is reading this. First of all, I'm sorry if i made a mistake on my english, I'm learning. My name is Andre I will tell a brief story of my life so you can understand my situation. My parents are peruvian and traveled to usa because of all the problems that Peru...

Hi all, I will be doing an experiment in which I will be rolling a basketball down an elevated ramp. After leaving the ramp, the basketball will free fall for 1.25m before reaching the ground. I was looking to come up with a theoretical trajectory for the motion of the ball, the issue is that I...

So I am a heavy vehicle mechanic. One of my vehicles has an air starter with a separate air tank dedicated to the starter. This tank is fed from the main air tanks on the truck with a check valve to only allow air into the starter tank. The gauge on the dash only displays the pressure in the...

New to forum Most air tanks are categorized on volume of air they hold . The question I have is this that a 5 gal air tank that holds 160 psi , is it equivalent to a tank that holds 2.5 gal of air at 320 PSI ? if not then is there a formula to figure this ratio . Thanks

I should be able to do this, but its been a while and maybe I'm making this more difficult that it should be. Assume you have a cylinder nearly sealed but with an outlet hole at the top. I want to pump a fluid into the canister, pushing the air out of the hole, and time how long it takes. The...