DIY Solar Panels

I know this problem doesn’t involve any heavy math but for some reason I can’t quite figure it out. Any help please?

Find wind speed (x) and airplane speed relative to the air (y).

DATA

West to east travel time: 1.5 hours
East to west travel time: 2 hours
West to east total mileage: 500 miles
East to west total mileage: 500 miles

Use the information below to calculate.

Find wind speed (X) and airplane speed relative to the air (y).
West to East Airplane speed relative to the ground = x-y
East to West Airplane speed relative to the ground = x+y
Distance traveled = speed * time

the true airspeed of the plane is 291.5 mph
if constant for the entire trip,
the wind speed is 41.5 mph (from the west).

relative airspeed…
291.5 + 41.5 = 333 mph, eastbound
291.5 – 41.5 = 250 mph, westbound

333 mph x 1.5 hrs = 500 miles
250 mph x 2.0 hrs = 500 miles

I am trying to calculate a power of a Savonius wind turbine. According to the formula which I am going to use
Power AVAILABLE in the wind = .5 x air density x swept area x (wind velocity cubed)

Even though I am using this formula. I am bit confused because I am using three blades on my design and There might be at lest 1 blade which will be rotating opposite to wind direction. I think this formula lacks the opposite force aswell. Could anyone please correct me am I using the right formula too?? Thanks

Each wind turbine design has a power coefficient that demonstrates that maximum power available in that particular design (See Betz limit, 0.59,of a wind turbine to know a little more of what I’m talking about). A Savonius wind turbine’s power coefficient is approximately 0.15, which is the lowest of all wind rotor designs.

Firstly, you are using the right equation. The amount of blades used in the design has no effect on the swept area, so don’t worry about that. Its just the area that the blades will pass through while rotating, typically a circular area. The power coefficient will factor in the blade moving in the opposite direction.

After performing the above calculation, multiple that value by 0.15 to determine the MAXIMUM AVAILABLE power. This value does not include any loses associated with the gearing, structure, etc. It will be the ideal number that you cannot realistically obtain.

Overall, you are using the right equation but you need to incorporate the power coefficient. I have a graph of all the wind rotor designs that I wish I could post here. Hope this helps!

I am building a wind turbine and cant figure out how to calculate a torque of the wind turbine. For power I use Power =0.5 x Swept Area x Air Density x Velocity3
And the average wind speed is 11mph or around 5 m/s.
Air Density = 1.23 kg/m3

Hey Spy, your other answers here are on the right track, if it s tourque you are trying to acquire, you can take the watts you are expecting, or HP, and divide out the RPM to convert power output to torque. My guess is you don’t know what power to expect, and this is how you are trying to determine that. I have to ask a question: What are you using the turbine for? I’m hoping it isn’t for power production. Vertical axis turbines are handy for lots of interesting things, like pond pumps and wind chimes, but the reason you don’t see the power companies putting them up is because of their horribly low efficiency. Most turbines operate today in the 25 – 30 % range. There is a theoretical limit of around 39%, called the Betz Limit that no turbine can operate beyond, but the vertical units, such as a, "Darrieus," rotor, generally run in the 5 – 8 % range. But you don’t need to take my word for for it, check out the source and read the articles and formulas yourself. Your formula does not seem to have an efficiency variable in it, they do at the American Wind Energy Association website. There is a great article by Mick Sagrillo at their website about the vertical axis rotors worth reading before you build one, I will list sources below. Good luck with the project, and take care, Rudydoo

The earth’s surface is slow to heat up or cool down primarily because of ____________________.
the low heat capacity of water.
cloud cover.
X the high heat capacity of water.
the balance of solar radiation as the earth experiences night and day.

Question 2
How do we know that fossil fuels have caused global warming?

chemical additives used in fossil fuels are found in the stratosphere.

X. The 14C/12C content of stratospheric carbon dioxide is very much lower than that of the troposphere.

The chemical bonds holding the carbon dioxide together are weaker because they have aged.

The connection is only theoretical and has yet to be shown.

Question 3
The tilt of the earth on its axis affects ____________________.
X the earth’s seasons and the length of daylight hours.
the earth’s revolution around the sun.
the frequency of hurricanes.
the brightness of auroras.

Question 4
The earth’s surface and lower atmosphere is warm because ____________________.
long-wavelength terrestrial radiation escapes into the atmosphere.
of the earth’s close proximity to the sun.
of the balance of incoming long-wavelength solar radiation and outgoing short-wavelength terrestrial radiation.
X. atmospheric gases (such as water vapor and carbon dioxide) trap and absorb infrared terrestrial radiation.

Question 5
Global warming is caused by ____________________.
the depletion of the ozone layer, allowing increased ultraviolet radiation to reach the earth’s surface and heat it up.
the melting of the polar ice caps, which cool the atmosphere, resulting from decreased salinity in the ocean.
X. increased amounts of CO2 and H2O in the atmosphere, which absorb the earth’s radiated heat.
increased hot air flowing from politicians world-wide.

Question 6
Temperature increases with altitude in the
troposphere and mesosphere.
stratosphere and ionosphere.

troposphere and ionosphere.
X. tropopause.

Question 7
The temperature of the mesosphere increases from -100oC at the top of the layer to 30oC at the bottom. This change in temperature is a result of
solar radiation being absorbed by ozone.

more heat from the earth’s surface at the lower altitudes.

X. carbon dioxide creating the greenhouse effect.

interaction of the magnetosphere with the tropopause.

Question 8
If the earth is closest to the Sun in January, why is much of the northern hemisphere cold in January?
It is cold because it is winter.
The southern hemisphere is tilted away from the Sun in January.
Solar energy favors the equatorial regions.
X. The northern hemisphere is tilted away from the Sun in January.

Question 9
In the Northern Hemisphere, air rushing into a low-pressure region
spirals in a clockwise direction.
sinks.
X. spirals in a counterclockwise direction.
rises.

Question 10
Many of the world’s larger deserts are the result of
the Coriolis effect pushing moist air upward.

extremely high temperatures that evaporated all the water.
X. strong prevailing northwesterly winds.
belts of high atmospheric pressure preventing air movement.

Question 6
If you substitute "thermosphere" for "ionosphere"

http://en.wikipedia.org/wiki/Earth%27s_atmosphere#Principal_layers

… stratosphere and ionosphere is then correct.

Question 7
None of the above, with "solar radiation being absorbed by ozone" being closest (nitrogen and oxygen are actually responsible for the absorption, as ozone is barely present in the thermosphere)

Question 10
I don’t like any of those answers, but I like "extremely high temperatures that evaporated all the water" best. A case of positive feedback…

i know i have to use the equation:
Power = 0.5 x Swept Area x Air Density x Velocity3
where velocity is the wind speed and air density is 1.225 and the area swept depends on the radius of the blade of the wind turbine (Area swept = pi * r^2)

Depends on the size of the wind turbines, they come in all sizes from 1 kW to 5 MW.
also need to know the percentage output of each wind turbine, ie, if a turbine is rated at 1 MW, what is the average output.

The equation has nothing to do with the solution.
10GWh/year x 1 year/8760 hours = 1.1 MW average output

So if the turbine is operating 100% of the time, one 1 MW unit will do.
If it is operating only 20% of the time, then you will need 5 1MW units.

.

The question is…With a tail wind, a helicopter travelded 300 miles in 1hour and 40 minutes. The return trip against the same wind took 20 minutes longer. Find the wind speed and also the air speed of the helicopter.
Please help I’m stuck on this. I know that distance= rate x time

distance = 300 miles
Time = 100 minutes

plug in

300 = r(100)
divide by 100 on both sides
rate = 3

300 = r(120)
divide both sides by 120
r = 2.5

a) is the air pressure above the roof lower or higher than the pressure inside the house? Explain
b) whats the pressure difference?
c) How much force is exerted on the roof?

Thanks

bernoulli principle stated that in the atmosphere when pt#1 has high pressure and pt#2 has low pressure, the difference pressure created wind velocity blowing from high pressure point to low pressure point according to the following formula
p = (1/2)(d)(v^2)
p = pressure difference in N/m2 or Pa
d = air density 1.29 kg/m3
v = wind speed m/s

also bernoulli stated that still air has higher pressure than air in motion, which means that inside the house the pressure is higher than outside, the wind blows from inside to outside causing the roof to be lifted (not collapsed), as most people think

(a) and (b)
let p = pressure difference
p = (1/2)(1.29)(33.33)^2 = 716 N/m2 (or Pa)
pressure above the roof = 101325 – 716 = 100 609 Pa
pressure inside the house is still air at 101325 Pa

(c) lifting force on the roof = (p)(A) = (716)(70) = 50157 N

A commercial airliner traveled 2200 miles with the wind in 7 1/3 hours (that’s 7 and one third hours) and took 10 hours to return the same distance against the wind. Find its airspeed in still air and the wind velocity.
I’m not asking for the answer to this question because I know that it’s better if I answer it myself. But I’m stuck on what the let x and let y equal statements would be.

Let x = airliner’s speed in still air and y = wind speed.

I’m really not getting how to solve bigger r*t=d problems. Here’s an example from my homework.

Flying with the wind, a plane travels 1200 nautical miles in 4 hours. Flying against the wind, it travels 500 nautical miles in 2 hours. What is the speed of the plane in still air and the wind?

Let x=the speed of the plane in still air
Let y=The speed of the wind.

Can you solve and explain how exactly you solved? I have nine more of these to do, and I could really use some help.

Thanks so much!

flying wid the wind effective speed will be x+y. speed is distance travelled divided by time taken. so x+y is 300miles/hr. effective speed flying against the wind is x-y. so x-y will be 250 miles/hr. now solve these 2 equations in x and y to get their values. from 1st equation x=300-y. put this value of x in 2nd equation to get answer.
x=275 miles/hour
y= 25 miles/hour

Im looking for some good Anime to watch. It needs to kind of recent so that the quality dose not suck.

these are some of the Anime i have Already seen or i am watching.

naruto,naruto shippuden (really like)
bleach (really like)
shakugan no shana (really like)
fate/stay night (really like)
kaze no stigma (really like)
zero no tsukaima (really like)
vampire knight
air gear (really like)
buso renkin
shining tears x wind (really like)
zoids ( i no its old but i still love this)
fullmetal alchemist (it was ok)
fullmetal panic, the other full metal panic season i forget the name.
true tears
school days
D.gray man

and alot of others that i cant remember right now
I also was watching the one called claymore but i didn’t like it so i stopped watching.

from the ones i have listed i guess i like anime with

magic
action
adventure
a little romance-pervertedness never hurt
and all that good stuff

if it is old i might watch it still so don’t be afraid to throw some oldies in here
sooo now i need some names people
what are some other good animes like these?
i do not mind subs at all
oh yea also i have seen

soul eater and i really liked it

The Wallflower
Baka to Test to Shoukanjuu
Katekyo Hitman Reborn
Detective Conan
One Piece