Air Definition and 1000 Threads

Homework Statement (a) Explain how heat is lost from a hot surface to the surrounding air. The Attempt at a Solution We will assume as there has been no other stipulation that the effect of radiation is negligible and thus we are taking purely about conduction. We will also assume as there...

What is wrong here. If I double speed drag will be 4 times higher. The engine needs to put out approximately 4 times more power. Energy consumption will be 4 time higher for a specific time period. However if it is a fixed distance I will arrive in half the time an the energy consumption will...

Homework Statement Homework Equations Equations posted in pictures attached The Attempt at a Solution I haven't attempted it yet because I am confused about something. If the-cv^2 case is for objects that hit terminal velocity at the fastest rate, why are my graphs showing that I should use...

Hi. If I fill a glass with water up to the top and close it with a coaster, I can turn it upside down without the coaster falling off and spilling everything. Usually, this is explained with the atmospheric air pressure being bigger than the pressure of the water inside the glass (hence, it...

Methanotrophs already exist in most soils. If we expose them to more methane, will they eat more? A solar powered fan blowing air down a tube that ran along under soil, with lots of small holes along its length - would that reduce the methane in the air? As a second part to the question, does...

A smooth flexible tube 1mm in diameter and 1 foot in length holds air at normal / atmospheric pressure (14.7psi). the tube is open at one end. the other end is connected to a tank by an open valve. the tube is peristaltically compressed so all the air in the tube is forced into the tank. the...

Homework Statement (a) A parallel plate capacitor has area A = 1 cm2, a plate separation of d = 0.01m, and is filled with air. If the breakdown field is E0 = 3 × 106V/m, calculate the maximum voltage and charge the capacitor can hold. Homework Equations dielectric constant of air = 1 Q=CV...

Greetings I am asking about the reliability of using a thermal gun to check if there is passing downstream the valve. The fluid is either steam or air. Wouldn’t the pressure and temperature drop sharply downstream the valve if it is closed but passing ? again I am talking about air or steam...

For thermal expansion in a bottle - is there a theoretical model on the pressure exerted on the inside of the bottle due to the air inside expanding when the bottle heats up. The air will be expanding randomly in all directions so the pressure exerted at any point on the inside of the bottle...

Hi there, I am new here so please don't be too hard on me yet and move this post if i placed it in the wrong forum. I am developing a little experiment game and i want the train to drive using real physics, but I am really bad at physics. So my question is is how do I calculate the friction of...

Hello! I am a high school student who is going to attend college this year (Phyiscs major). I was curious about the career prospects of being an Air Force Physicist, like what kind of work (research etc.) does one do, average salary, career prospects etc. Also, does one need to go through the...

Homework Statement Air with an initial volume of 0.12m³, pressure 1 bar and temperature 18°C is compressed according to the law pV1.3 = c through an 8:1 compression ratio. It is then allowed to expand isothermally back to its initial volume. Determine: i) the pressure and temperature after...

Homework Statement I have found a differential equation that models a non-linear pendulum with air resistance, and now I have data. I've looked at the following site for guidance on how to analyse the data. It compares the motion of a damped spring, and compares it to the motion of a damped...

Homework Statement Theses questions have been modified to solve my own inquiries. The originals can be found in the attached file. A parallel plate capacitor has area A = 1 cm2, a plate separation of d = 0.01m, and is filled with air.(a) If the breakdown field is E0 = 3 × 106V/m, calculate...

$\textsf{A juggler performs in a room with a ceiling 2 m above hand level.}$ $\textit{a. what is the maximum upward speed she can give a ball }$ $\textit{without letting the ball hit the ceiling.$\displaystyle 6.26 \frac{m}{s}$}$ \begin{align*} v^2&=2(9.8)(2)\\ &=39.2\\...

I am trying to understand the working of simple hydrogen fuel cell. We have anode (negative terminal), cathode (positive terminal), catalyst at anode to separate negative and positive ions of hydrogen atoms and electrolyte which allows only positive ions. We will be sending hydrogen fuel at...

Homework Statement I need to come up with an equation that would model the motion of a non-linear pendulum with air resistance. [/B]Homework Equations Fc=mgsintheta Fdrag=(1/2)p(v^2)CA The Attempt at a Solution I started with mgsintheta-(1/2)p(v^2)CA=ma After substituting v=r*omega and...

I was wondering about the microscopic reason warm air rises up, while cold air comes down. I am aware of the macroscopic reason - density changes. But what happens microscopically? Decrease in density means that the gas molecules are widely spaced out, but their mass remains the same. Then why...

I cannot understand the expression "air does not intervene with radiation". Would you please explain what it means in detail? " Considering that air does not intervene with radiation and the person is completely enclosed by the surrounding surfaces, the net rate of radiation heat transfer from...

Hello, this isn't actually homework but I have no physics/engineering background and can't solve this question for a DIY project: 1. Homework Statement I have a 2' tall, 16' wide door that is hinged/hung from the top (like an awning window scenario) so all of its weight is supported. The...

Positing an empty container, underground, with a static temperature of 50F (both container, earth, and air temperature) and a volume of X... and introducing (and displacing) into this container a parcel of 30F air of volume Y (which is less than the volume of X)... Is there any way to...

We did an activity today in class where we placed an empty 2L bottle in the Freezer, let it contract, then calculated the coeffcient of volumetric expansion using ΔV = VoβΔT. We got pretty close to the accepted value. The question is... Does the coefficient of thermal expansion only work for...

Homework Statement I am working on a problem where I need to determine the time taken for an air heater with an 8kW output to heat a volume of air of 9m^3 by 25C. I am neglecting all losses at the moment. It almost seems too simple in my mind that I'm concerned I'm overlooking...

Homework Statement If the velocity v of the air in a boundary layer having a dynamic viscosity of 18x10-6 kg/ms is given in terms of the distance y from the surface by v = ay + by2 where a and b are constants, calculate the surface shear stress if at 1.5 mm from the surface the velocity is 75...

Hello Physics Forum Community! It sure has been a while! :) I have been hard at work on my goal; to create a spreadsheet that simulates the Internal Combustion Engine (Spark Ignition). I can't take all the credit for having come this far, so there will be links to a few sources below that I have...

Hiya! I'm an ameture "maker", and recently I've become interested in air pressure and such. I thought a fun project to help me learn about it would be to make one of those small air cannons that are powered by bicycle pumps (safety first and all that). One thing confuses me though: how exactly...

Hi there, prob a simple question for you physics gurus, but this application is for a race car, and question relates to air flow velocity through a pipe, in particular exhaust and intake. Now, my thinking for the exhaust (push) is that by going from a small diameter to a large diameter will...

I have noticed that cold air makes far away objects, such as mountains, appear closer than they do in warm clear weather. Does anyone have an explanation for this?

Homework Statement The hydrostatic equation expresses the change in pressure dp due to a layer of atmosphere of thickness dz as constant volume. ##dp = −\rho g dz ## Using this expression, show that the change in temperature with height for a parcel of air that rises adiabatically in the...

I have an industrial application where 20kW of heat is being wasted, which is painful to watch. I have learned already that low temperature turbines just don't work, so would like to check some ideas and better understand how air motors/turbines work. I have also learned so far that...

Alright so I'm a freshman in college studying physics with astronomy specialization. I want to eventually get a PhD and work for a space agency or maybe even become an astronaut. I've been told that having experience in the Air force looks much better when applying to work for a space agency...

Homework Statement A tank of constant volume V contains air at an initial density pi. Air is discharged isothermally from the tank at a constant volumetric rate of Q (with SI units of m^3/s). Assuming that the discharged air has the same density as that of the air in the tank, find an...

Please can someone explain me how high levels of ultrasound can be created in Air? Should we consider the Ultrasound or we should concentrate only on sound level in Air as frequency ultrasound have no effect on sound level?

Certainly a wooden ball and a stone fall with the same velocity. Would a balloon of cold air fall with the same velocity as a balloon of hot air? As a corollary, why does hot air rise over cold air? If you claim that cold air is denser, then the same argument fails when you compare a wooden...

Not sure if this is more appropriate for physics or for differential equations, but this problem centers around an airplane traveling with air resistance. I am not looking to get the most realistic-possible model, as it is just for a video game I am making. Although this is technically a PDE...

Hi! As we know air bubble in the water rises due to buoyancy and quickly reaches its terminal velocity. What is more, as bubble rises the pressure decreases, consequently the volume of the bubble increases resulting in buoyancy becoming larger. So the terminal velocity doesn't remain constant...

I created a model on autodesk inventor of a concept model kite that would stay in high altitudes and take in wind energy through the cone opening. Is there any advice you can give me about the aerodynamics of this model? (There are balloons that provide lift above the wings, and I want the...

I have a fabric from a windshirt testing at 40 CFM under ASTM D 737 (125 Pa). I am interested in understanding what would happen to air velocity if two layers were stacked and tested. Next, how would the results be affected by an air gap between the two layers?

Homework Statement You're in Paris, working on your first novel and short on cash. The owner of the cabaret downstairs has offered to take care of your rent if you'll help her design a climate control system for the place. It gets too hot and damp in the summer, and too cold and dry in the...

1. The problem statement, all variables and given/known I have absolutely minimal concepts of this subject so if somebody could help me with the most simple language I'd really appreciate it. I'd like to know how to calculate the volume of air I would need in order to be able to safely float...

Homework Statement I am working on a math investigation which involves the physics of the flute and I can't move on unless I find an equation for the change in required velocity of the air stream to produce different frequencies. I have a feeling I might have to abandon this idea and do...

Homework Statement The object is falling vertically in a strange fluid, the magnitude of the air drag is best described by the following FD = bv+cv2 where v is the speed of the object and b and c are constants. A. What are the dimensions of b and c B. If the object has mass m find an algebraic...

So i have been looking at a 1microsecond pulsed 250milliwatt 980nm laser. I watched a video where a guy outputed 50millijoules at 5 nanoseconds and achieved air breakdown. I am wondering since maybe mine is higher energy it will do the same or i need faster pulses?

Homework Statement I have a CAES system that takes air at a pressure of 102.2kPa and temp of 24 degrees C. It is compressed to 85 bar adiabatically at a rate of 168 kg/s. I know that Cp = 1.005 kJ/kgK and Cv = 0.718 kJ/kgK. The question is - determine the amount of work consumed by the...

How does low ambient pressure effect on the thickness of the boundary layer for given flow conditions of gas? In absolute vacuum the thickness of the boundary layer is 0 of course, but it seems that all the boundary layer thickness correlations use the Reynolds number, which doesn’t change much...

Hi, I'm a little confused about the theory behind this problem related to fluids/Bernoulli's equation: "An airplane wing is designed so that the speed of the air across the top of the wing is 251 m/s when the speed of the air below the wing is 225 m/s. The density of the air is 1.29 kg/m3...

How are we able to move trough the aire if the air exerts a force equal to the friction we use to push us through air? I´ve had this problem in my mind since some days now. I did this picture: url: https://www.kn3.net/60DAC45480AJPG.html

I know there are many factors that affect this question, such as altitude etc, but in its simplest form... - How fast does a parcel of air rise if, say, the parcel of air is at 5 degrees centigrade in a room filled with air at 0 degrees C. (Maybe I should be using Kelvin?). Just need to get an...

Hi guys, I came upon a definition of Non Newtonian fluid that is any fluid which doesn't deform linearly with increasing stress. But then if you think about fluids, pretty much every fluid acts like this, depending on whether you're actually capable of generating enough force to see it happen...

Homework Statement 1.Since the roadster seats only two people, it has only two side windows--one on each side. Each window is aligned squarely on the vehicle, so air can flow straight past the window as the vehicle heads forward. However, the air flowing around the roadster's windshield has to...