Wind Definition and 861 Threads

Hi everybody, this is my first post on your forum and i hope someone can help me :) the problem is i can figure out how to approuch this problem :s i do know that the process of the air descending is adiabatic but still i can't get it :( thanks for your help guys in advance. Homework...

i'm currently discussing this with a friend. anyway. here is the conversation: he said It started as "If something doesn't have a mass, it cannot have a force", due to Newton's second law, F = ma (Force = Mass x Acceleration). Logically, if you substitute 0 in for the Mass, you will get a...

What are the percentages of types of generators commonly used in wind turbines? To clarify, what percentage are regular squirrel-cage machines? What percentage are doubly-fed machines, permanent magnet machines, synchronous machines, and so on. I'm looking for a general idea of these statistics.

The Basis of this question is that: * Rockets launched at an angle follow the path of a rectangular hyperbola when thrust greater than their mass is produced. * That rockets fall in the path of a parabola when thrust is no longer produced, this only applies when the rocket has both x and y...

What is the effect of wind turbines on the aerodynamic of the wind system? Since energy is conserved, will excessive turbines lead to a leakage of wind energy and transformed into mechanical energy? [or concert to heat?] Also, what is the effect of the local pressure? Thanks in advance.

Hey Physics Forums. This is my first post here, and I'm just wondering about how to find what the initial velocity SHOULD be based on all the other information that I provide (it's for a program application I coded). Anyways, I have this right now (which is for no wind/0 wind): I am just...

Homework Statement http://img198.imageshack.us/img198/3834/relativeboatvelocity.jpg The note says "( Wind relative to boat is irrelevant! )" Why is it irrelevant?

I am trying to create a wind sculpture and I could use some help. The sculpture will have 3 points of rotation all driven by the wind. Visualize the letter "Y" and you will have the basic idea. The base has bearings allowing rotation as do both of the arms. My prototype model works to some...

I am an artist not a physicist, I do very much interactive art though, and as I am a bit geeky, I really love to get some physics tricks involved somehow. People get excited when there are little gizmos going and its just great! So this project that I am working on has me stumped...I want to...

Can you help with this question? I have a solid tube 10'D x 5'L with 2 42" drum fans in one end producing about 19,000CFM each. I need to know what the velocity will be at the end of the tube in M/S. Also, will the fans be more efficient if there is a seal around the opening where the fan...

I live in Wisconsin and I am looking for a wind tunnel where I can conduct a number of airfoil experiments. Since I am in high school, I am not yet affiliated with a university, so it is difficult for me to get in touch with lab technicians at universities. I have successfully contacted the...

Homework Statement Ok, an airplane weighs 6,000 (think of the airplane as a triangle) and one of the back two wheels is stationary and acts as a pivot. The airplane is on the ground. How fast does the wind need to be blowing to push the front wheel 90 degrees from the original location...

http://www.cnn.com/2009/TECH/science/06/16/high-altitude.wind.power/index.html Basically two designs, one a helium-filled turbine. The other would be a kite that goes up and down. Is this feasible? I see a major issue being the weight of cable that the device would need to support.

Hi all, I just looked at a thread involving a wind turbine on a car or something of that sort and I have a similar idea... but it does not involve a car. It is similar in the aspect of something creates energy , and you add something else to it to get more energy, but I'm not sure if the...

I'm pretty sure someone somewhere has already built one, I've gone over the concepts involved and it does seem both practical and possible. The idea is this: electric-powered car that is recharged by several wind-generators(essentially fans on the roof) that recharge the batteries once the car...

The below though experiment which i devised, raises some personal concerns about my understanding of thermodynamics and aerodynamics, based on the fact that they seem to predict different outcomes. If anyone out there could offer some insight into what would actually happen, it would be greatly...

I'm looking for a summer project and I'm thinking of building a wind turbine to generate additional power for our home. I want it connected to the grid so that it runs our meter backwards for times where we arn't using more power than we generate (on vacation or something, electric company has a...

I have a question about Reynolds Number and wind tunnel tests. Last semester a few students at my university were conducting wind tunnel tests on a small model of a truck, they were trying to find ways to reduce the drag in order to save fuel. I would guess they were testing at a Reynolds Number...

1.A hurricane wind blows across a 7.8 m x 12 m flat roof at a speed of 180 km/hr. What is the pressure difference? How much force is exerted on the roof? 2. Homework Equations P= p_atmos + pgd P=F/AThe Attempt at a Solution p = 101300Pa - (1.3)(9.8m/s^2)(93.6m^2) p = 100107.5Pa 100107.5Pa =...

Consider a 10 m/sec wind blowing against a perfectly rigid wall. I want to calculate the pressure the wind produces on the wall. I'm ignoring the details of the actual physics of compression and turbulence. I'm reducing the problem to one cubic meter of (incompressible) air with a mass of 1.2 kg...

Hello, I'm a senior year ME undergraduate and I'm building a low speed (velocity=30-45 m/s) wind tunnel for my college as a final year project. The initial size for the tunnel was 300mm x 300mm in the test section with an open circuit configuration. I've read some papers on the design...

A windy 0 °C day perceived as colder than a 0 °C day without wind. I find that strange, given that wind is just air particles with kinetic energy. When those speedy particle hit a body, they should give off some of their energy to that body in the form of heat. But instead cold is perceived by...

How does Wind speeds change as a function of elevation?

Im new to this forum and wanted to see what you think about my new patent pending design. My concept is...using a 2.5Mw wind turbine, refit 110'L rotor blades with a 10-12' diameter of concave vanes or paddles designed to capture max air thru a forced ducted system that is generated from a large...

As I live not far from Altamont Pass and often hike the wind energy area, I see the damage windmill blades do to birds by the number of dead ones on the ground. Also, these windmills are truly Star Wars ugly and insulting to the environment visually, not even considering what they do to birds...

1. A weather balloon travels upward for 6 km while the wind blows it 10 km north and 8 km east. Approximately what is its final displacement from its intial position? I am not sure how to look at this. I know they are vectors which makes this a bit complicated and I know I have to use...

In my current experiment, I am using a wind tunnel to test laminar flow over airfoils of various designs and at various angles of attack. My current dilemma is in deciding how to construct the airfoils. I am looking for a method that is precise and realistic. (At this stage, I am not worried...

Homework Statement 1. A wind turbine with a swept diameter of 20m and an efficiency of extracting energy from the wind of 40% is subjected to an average wind speed of 10m/s. (a) How much power might the turbine produce? Please can some one point me to the right equation as everyone I...

http://www.msnbc.msn.com/id/30448774/ This story rocks! The dog, named Tinker Bell (you can't make this stuff up!), was blown away by a strong wind. She was eventually found...with help from a pet psychic. Nice.

Hi, I have been toying with the idea of producing electricity from the cross winds that build up in my house. Basically when I leave a window open one one side of my flat and open a window on the other the wind blows through the house very strong. I want to place a wind generator on one...

Could someone please give me an answer with a scientific explanation for: Would a stationary vehicle or the same vehicle moving straight, at speed be more likely to be flipped over onto its side/roll when exposed to a strong gust of wind blowing at its side ("approx. perpendicular to the...

Why does the wind blow off the ocean during the day at the beach, and off the land during the night?

Homework Statement assume that the rotation period of saturn at the equator, very deep in the atmosphere is 10 hrs. higher in the atmosphere, the equatorial winds blow west to east at 250 m/s. What would be the rotation period of this higher level in the atmosphere? also know - maximum...

I have been trying to find answers to this but have had no luck so far. I'm hoping these forums can help me out. I have some specs for an antenna and need to decipher what the wind loads mean. I have attached a picture below. Basically, what does the Fa, Fs, and M mean? Thank you in advance!

for a physics project i am designing a vertical wind tunnel made out of stovepipe and powered by a leaf blower. this experiment is designed to find the terminal velocity of different shapes. We already have a way to vary the wind speed, but what we don't have is an accurate way to measure this...

Homework Statement An airplane pilot sets a compass course due west and maintains an airspeed of 220 km/hr. After flying for .5 hr, she finds herself over a town 120 km west and 20 km south of her starting point. Find the wind velocity (magnitude and direction). Homework Equations...

Even though I’ve experienced the evidence firsthand I’ve never quite been able to totally accept that the treadmill and turntable tests accurately represent a cart being powered solely by wind (like many others). So I’ve built a circular wind tunnel to test DDWFTTW in a “real” wind and the cart...

It seems to me that an obvious source of dark matter (and possibly dark energy) might be the massive ejections of spent fuel from our sun in the form of the solar wind. If our sun regularly ejects spent fuel in the form of the solar wind, it follows that the same process must happen in billions...

Homework Statement A 2500kg car is traveling 35mph into a head wind gust of 28mph. The wind gust lessens to 16mph. How many seconds will it take for the car to reach velocity of 50mph assuming the force applied to the accelerator throughout remains unchanged?Homework Equations The Attempt at a...

For a school science project I am supposed to design an experimental process that utilizes the wind tunnel my school owns. I've built four small model towers out of wood - one a triangular prism, one a rectangular prism, one a cylinder, and one a pyramid - that all have the same height and base...

Homework Statement A moderate wind accelerates a pebble over a horizontal xy plane with a constant acceleration a = (6i + 7j)m/s^2 . At time t = 0, the velocity is (3i)m/s . What are the (a) magnitude and (b) angle of its velocity when it has been displaced by 12.0 m parallel to the x axis...

Mmmmmmmmmmmm yeah.... not everyday you get to use one of these. I'll post more pictures once we start running wind tunnel tests. I'm 6'4", each red blade is as tall as I am. http://img509.imageshack.us/img509/1333/pict0389.jpg http://img15.imageshack.us/img15/2746/pict0388v.jpg...

I've been searching the internet far and wide but cannot seem to the wind speed information I want. I need a graph or table of wind speed vs. time, where the time scale is very small, on the order of seconds. I did find one graph here...

Hi, I'm trying to build a vertical wind powered turbine system and I'm have trouble finding a small, cheap generator/alternator to use. Does anyone have any suggestions?

Hey guys, new user here. I had a question about a project I am working on with a professor. Unfortunately he does not have much experience with fluent but is a very intelligent and experienced person when it comes to the theory. So I am basically trying to develop a chart of the power...

On May 10-12 1999 it has been stated in a website that the Solar Wind Disappeared. It stated that 98% of the total solar wind stopped but the piciures of the the SOHO satellite looked normal. Is this true or a crackpot site? The polar borialis was said to be strange and a phenonema of...

For years I have been wondering why wind turbines are designed with very skinny blades (photo http://en.wikipedia.org/wiki/File:Turbine_aalborg.jpg ). Most of the available wind passes right through the circular "reach" of the device without touching the blades. Wouldn't it be more efficient if...

I have come unstuck in my coursework project, and cannot find any information/equations for the effects of shielding on wind loading in a structure (This is not an ordinary structure, it is an unsymmetrical sculpture made up of circular and Universal beams). So i would firstly like to find how...

Homework Statement A plane attains an airspeed of 620 km/hr. The plane sets out for a destination 1085 km to the north (a 0° course) but discovers that the plane must be headed 20° east of north to fly there directly. The plane arrives in 2.00 h. What is the wind speed? What is the direction...

I am trying to charge a battery using wind power! but i can't seem to find anything telling me how i can determine the power output coming from the generator, when all i know is the wind speed.. i know that the blades on the fan will have to be small but using the right gears with the high speed...