Wind Definition and 829 Threads

Homework Statement The graph shows the speed as a function of time for a minivan, coasting on neutral along a straight, level road, loaded with windsurfing equipment and towing a boat. The total mass is 2500 kg, weight= 5512lbs. Find the size of the force due to wind and rolling friction when...

HI folks, new to this forum.I posted this on a different thread, but this seems the better location... it's a conceptual question. I'm in a Fluid Dynamics class and need to make a presentation on Bernoulli's conservation of energy equation as it applies to wind turbines. I think I...

HI folks, new to this forum. I'm in a Fluid Dynamics class and need to make a presentation on Bernoulli's conservation of energy equation as it applies to wind turbines. I think I understand the different energies involved here: kinetic(v^2/2), pressure(P/rho), potential(zg)... I want to...

Hi everyone…. I’m trying to evaluate the feasibility of putting what is essentially a wind turbine inside a horizontal exhaust shaft. I have a feeling that this would affect the volume flow rate through the shaft, but am having difficulty proving it. I have found plenty of textbook examples...

I am building a small wind tunnel, and I have a few questions about it. First: The Fan I am using produces 800cfm and is 12'' in diameter, I am going to narrow it down to 6''. The calculated wind speed that I got was 74.5km/h. Can anyone back me up on this? Second: When I use scale models...

I feel that this may be a silly question, but, Does wind affect how far sound can travel? I know that the air temperature affects how far a sound can travel (does wind affect air temperature?), but what about wind? I tried to find an answer via google, but I haven't found anything...

On my homework is says "On the Beaufort scale of wind force, the term "fresh gale" describes wind speeds from 39 mi/hr to 46 mi/hr. Write a compund inequality to describe "fresh gale" wind speeds." Would an acceptable inequality be {S: 39 < S < 46} ?

Does anyone have any good suggestions or design ideas. I have an idea in mind but outside input and help would be much appreciated. The site that has the project details is http://www.manchestertwp.org/teacher/mths/pwhite/Physics_files/physics%20oly%202006%202007/EVENT%205.mht .

Ok, doing a project at the moment and this is one of the issues I have to overcome; The information I have researched is as follows: If this is the case then a 88m diameter rotor should generate 2400kW? But the below diagram from the same page shows a 80m diameter rotor generates 2500kW...

convection right?

Do fish---- Break wind, when looking at them in aquariums i have never seen bubbles coming from that end, so may be their digestive system works differently.

The question said that the airplane turned west for 255km/h, and the resultant was 225km/h South 70 degrees West. I have to find the wind direction and velocity. How?

Is it possible that one day, the Earth magnetic field get so weaken that solar wind could strip off water from earth? I ask this because of this article which leads me to draw the parallel. http://www.geotimes.org/sept04/NN_solarstorms.html

Recreating the Mythbusters' Terminal Velocity Wind Tunnel - Need advice on Manometer Hello, I am trying to find the terminal velocity of a projectile. I am placing the projectile inside a clear tube and blowing compressed air inside the tube until the projectile is hovering at some height...

Suppose the force of wind resistance is proportional to the speed of the object and in the direction opposite of the object’s velocity. If you throw an object upward, when is the magnitude of the acceleration the highest? a.It is highest at the top of its trajectory. b.It is the highest...

Relative velocity question -- plane and wind The distance between two cities A and B is l. An airplane travels back and forth between A and B, flying in a line, with velocity V relative to the air. (a) Find the total flight time, if the wind blows with velocity v, in a direction that forms an...

I can create/solve the math problem without any difficulties once I have diagram in place, but I am having trouble setting up the diagram so that I can visualize it. The questions is: A novice pilot sets a plane's controls, thinking the plane will fly at 2.50 x10^2 km/h to the north. If the...

Is there a (freeware?) program to calculate 3D lift and drag for simple flying bodies, e.g. ball, cylinder, cube, wing? There are programs to calculate lift and drag for foils (2D programs), e.g. javafoil of Martin Hepperle. Those programs could be used to study the flow in 2D only. E.g...

I wonder if anyone could shed some light or information about the subject I'm looking into. How will wind turbines with varied amounts of blades perform in varied wind speeds. E.g. the less amount of blades you have the better a turbine will perform at higher wind speeds? Any help on the...

Hello all, My boss wants me to create a form of short term wind prediction based off a collection of long term wind data. I haven't taken a course in statistics so this is totally new to me. Basically, the data is organized by Year > Month > Day > Hour > Wind Speed with data stretching back...

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...