Wind Definition and 861 Threads

http://www.quietrevolution.co.uk/ I understand these things can spin, but what I'm questioning is whether they can really produce enough power to even power themselves? I mean, there have got to be a few hundred if not thousand LEDs on each one, as well as a control circuit to control the...

hello everyone, Im new to this forum but i really need some help doing a physics assignment. I am trying to use Newtons second law and the equation for wind resistance(click link) to determine the the angle made by a specific velocity. The link to the assignment is...

Hi, With all the wind farms being put into production recently, does anyone know what the average size generally is. I see they are generally between 10-kW to 5-MW, quite a difference, so I would think the large ones can only be used in certain places and need to be spaced apart more - but I...

Does anyone know where I can find the magnitude of the force exerted by the solar wind? It's for a jackson problem (6.11, part b). He asks us to compare the radiation pressure to the corpuscular radiation. I've googled it and only found the velocity of said wind.

I believe the PDE Utt-v^2*(Uxx+Uyy+Uzz) can be used to desribe air pressure, and how this pressure changes during time (with a given pressure in t=0) My question is, does this equation also takes into account effects of movement of particles? Such as wind? Can it describe wind? Or do we need...

I know the basic answer, that the movement of air sets things vibrating which makes noise, but I don't know the specifics. For example, if the wind is blowing hard, you can often hear the wind howling at a certain pitch. This seems to be dependent on velocity because the harder the wind blows...

Any ideas how to start this problem (formulas or anything)? Just after its completion, the glass-walled skyscraper known as the John Hancock tower in Boston (see Figure P.64) was faced with an embarrassing problem: its windows kept falling out on windy days! The building soon became known as...

Hi there! I'm doing research for computer science and I have to simulate wind movement. Obviously, I need to know stuff about wind movement. I've tried several books and they haven't given me what I want. Most books have the whole "how do we make this airplane go fast" thing going on...

This has come up a couple of times now, and if true then this needs greater exposure and is certainly worthy of discussion. At a glance, this or some variation on the idea seems most promising. http://www.skywindpower.com/ww/index.htm It seems to me that the energy available in the jet...

Could not find a thread on this particular topic, but I want to verify my thoughts. I emailed my local Green Party rep in Canada here regarding his partys take on Nuclear Power. Our particular area of Canada is facing a bit of a situation where more megawatts NEEDS to be available in the...

I hate it when this happens! I'm down in my office and need to get up to the house, but the wind is howling, the rain has been pounding, and fairly large branches are flying around like missiles out there. They keep slamming against the walls of my office and scaring the heck of my poor little...

I was wondering if anyone would be able to answer this question for me: Where the the energy collected from wind power come from? Now I know that it comes from wind (obviously) but where does the wind get its energy? I was thinking the energy came from the Earth's rotation, and that...

Hi, I have second doubts on air drag problem. Let's say an object is moving with speed v_obj = 15 m/s and that the air is moving with speed v_wind = -2 m/s. What is the the force of air drag? If There would be no wind. The force would be 1/2*drag coeff.*density of air*area*v_obj^2. But...

the first one says, "the flag is moving." the second one says, "no, the wind is moving, and the flag is inert" the third says, "no, they are both moving, the wind moves and also the flag moves." a passerby hears their dialogue and says, "mind is moving." we can see that all movement is the...

I completed a wind tunnel test on a NACA 23012 aerofoil last week and am now writing a report on my findings! I need some help with working out the lift Coefficient as i seem to be going wrong somewhere. Cl= L/.5 ρ Vw² S To find the lift force i am subtracting the lift force which was...

a pilot maintains a heading due west with an airspeed of 240 km/h. After flying for 30 mins, he finds himself over a town that he knows is 150 km, W and 40 km, S of his starting point. What is the wind velocity at his altitude? how do i tackle this? i just a push in the right direction thanks

I am looking to design a few ‘wind powered’ gadgets, on a very small scale. I am struggling to calculate the power generated from a turbine of about 30mm diameter. I understand that the number of coils surround the armature has an obvious effect on the generation, but was wondering if there was...

A passenger on a ship traveling due east with a speed of 13.38m/s observes that the stream from the ship's funnels make an angle 20 (degrees) with the ships wake. The wind is blowing from south to north. Assume the smoke acquires a velocity(with respect to the earth) equal to the velocity of the...

Wind blows at an average speed of 5m/s 10% of the time. If the efficienty is 45%, what is the radius of the wind turbine that would be needed to generate 571 W of electricity. density of air = 1.25 kg/m^3 The formula is Power = η(1/2*pi*r^2*ρ*v^3), where η is the efficiency, ρ the density, and...

An aircraft heads due south with a speed relative to the air of 44m/s Its resultant speed over the ground is 47 m/s The wind blows from the west. A) What is the speed of the wind? B) What is the direction of the aircrafts path over the ground? I figured out a, 16.5 but i don't even know...

A pilot flies at 140 km/h. The heading is due East for 1 hour,due South for 1 hour, due west for 1 hour and due north for 1 hour. IF a steady wind blows at 60 km/h, how long and at what heading must he fly to return to the start point? The wind is blowing in a northwest direction

I would like a way to be able to observe the air flow through wind instruments. I was thinking a lab where the do tests on the aerodynamics of cars. any other ideas. also does anyone know of a facility in the New York area that might be capable of such a technique. I would like to video...

A boat with a windmill rotating a water propeller can sail directly upwind. It has been done many times, so take that as a given. (The maximum speed so far is about 0.5 times the speed of the wind. For a land yacht, the maximum speed so far is about 1.0 times the speed of the wind.) My...

Assume a windmill boat is drifting down a fast flowing river during windless conditions. It uses its relative wind to outrun the speed of the river. What is the correct way to describe this situation in terms of energy and power? Can we say that its energy is derived from the river but its power...

What equation represents the force of air resistance? Is it simply \vec F_{air} = c \vec v , or must the velocity be raised to a higher power? *Also, which equation represents wind resistance to an object, in the case where a wind is blowing relative to the ground ?

Ok so I have a ball tied to a string hanging. I start a fan and the string now forms an angle. I have heard that there is a relationship between the force on the ball and the wind velocity (obviously) It should be something like F=kv^2 or something like that, what I need to find out is the...

Stories about bird kills caused by wind turbines are common. I really don't see why this is a problem. It seems to me that something fairly simple could be done; lights, sound, optical effects using colored paints...something. Does anyone know much about this?

So I've read about these Lifters that lots of crazies attribute to antigravity or whatever. Obviously we know that it's caused by the ionic wind. But how does that work, exactly? http://www.blazelabs.com/l-vacuum.asp I read says that the high voltage of the top conductor ionizes air (by...

Why aren't pressure sensors used for measuring forces in a wind tunnel? Why are strain gauges preferred? Is it because strain gages are sensitive? The lift and drag plates attached to the stinger should feel strain in two directions. How come the strain gage manages to measure the strain of...

Okay, so here's the thing... D=\frac{1}{2}*C_D*r*v^2*A I need to find the Force pushing against a sign that is attached to a vehicle. The area (A) of the sign is 60"X28" which is 42.672 m^2 The velocity (v) that the vehicle will be moving is roughly 80 miles per hour which converts...

Okay, so here's the thing... D=\frac{1}{2}*C_D*r*v^2*A I need to find the Force pushing against a sign that is attached to a vehicle. The area (A) of the sign is 60"X28" which is 42.672 m^2 The velocity (v) that the vehicle will be moving is roughly 80 miles per hour which converts...

hey u lil smart asses, I have to start a really important project in like 2 days, (extended essay for those ex ib) and i have to investigate on airfoils in a wind tunnel, basically i have a lot of choice. I thought I could design a four-digit naca airfoil (tho it seems really complicated)...

hey all of you lil engineering smart asses, I have to start a really important project in like 2 days, (extended essay for those ex ib) and i have to investigate on airfoils in a wind tunnel, basically i have a lot of choice. I thought I could design a four-digit naca airfoil (tho it seems...

Hey, I'm trying to measure the lift/drag of a wing in a low-speed wind tunnel, the only ways i might know are using a load cell or force probs, but have no idea about how to set it all up and my school doesn't have the material. So please, can u give me any way using simple things to measure...

Suppose there were a nearby supernova, say 10 to 20 lightyears away. It's not close enough to incenerate the earth. Would such an event cause the solar wind to become swept away? If so, would there come a great earthquake as the wave went by the earth? I suppose that the gravity of such a wave...

I have a Thermo I problem: Given: 80m diameter wind turbine rotating at 20rpm under steady wind conditions at an average wind velocity of 30kph. The eff of the system is 35%. Need: Power generated Assumptions (made by me):delta PE ~0; mass=constant; operating at Steady Sate; T~constant...

So why exactly are wind turbines so expensive? I mean arent the generators alone $5-$10 million? One of my professors (hes just a physicist though) said he doesn't really understand why it costs so much either. The next week he brought up maybe there's sophisticated equipment making sure the...

Where did everyone go? I feel so alone here...

Part one: Supposed: A wind funnel. Circular Input radius = 600" Windspeed = 24 ft/sec Air weight = 2 lbs/yd3 Circular Output radius = 60" Disregard = backpressure. 1 HP = 560 ft lb/ sec Solve for = (1) Theoretical Wind speed at output (2) HP at output. Part two: Backpressure will...

I have a question I am pondering about. If there was a wind and the windspeed is faster than the speed of sound, would there be any kind of sonic boom effect created?

Hi everyone, I need to build a wind power generator for a grade 11 physics project, but i dont' want to spend too much money on it. Can anyone tell me a cost-effective way of making a wind power generator that works? Thanks

Can anyone help me with this question. I'm not really sure where to start. A wind with speed 45m/s blows across a roof 20m long and 12m wide. The pressure inside the room is 1x10^5 Pa. Neglecting the small difference in thickness of the roof, what is the net force on this roof due to the...

Ok I have built this car for a school project that is supposed to go against the wind. As there is a wind it should be able to drive into it (powered by the wind). Now the car is built and it is working. I have mounted a horizontal windmill that through gearing powers the back wheels...

Our local weatherman assured his audience that although the wind chill would reduce apparent temperature during that day, at night the wind would actually seem to warm a body. I am assuming he was not referring to an incoming warm front, or anything to do with cloud cover, just the perception...

I must construct a car which is propelled solely by wind energy. The car should be able to drive straight into the wind. Have you got any ideas?

I am a student in Malmö, Sweden currently preparing for the IYPT (international young physicists tournament) 2005 in Switzerland. We are supposed to do a 10 minute presentation, solving the following problem: Windcar Construct a car which is propelled solely by wind energy. The car should be...

why doesn't Coriolis force affect the wind speed but only the wind direction?

Wind Car Theory...for assignment... I am a student and i have to explain the wind car theory. I really need help. I need to come up with equations and real explanation. I'd be really happy if you could help me. You can email me at : ngkho@yahoo.com.hk Sorry again for posting my message here...

//It's the same as in college level help forum but it fits better here i think...// Now it's time for me and a friend to prepare our project for a physics tournament in school. The task is: Construct a car which is proppelled solely by wind energy. The car should be able to drive !straight...

An airplane pilot flies a plane that has an air speed of 450 mi/H. She needs to fly from Denver to Chicago, which lies on a line 1150 miles long at an angle of 25 degrees north of east (measured from Denver.) A constant jet stream of 280 mi/H is coming from the southeast (ie, along the 45...