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# AS wind turbine question, help! (with photo) watch

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1. okay this is doing my head there are three pages for the question but im sure i can work out the rest, its the (a) part thats horrid.

and here is the info
http://i919.photobucket.com/albums/a...e/DSCF1380.jpg

and the question
(a) Calculate the volume of the cylinder of air passing the rotor in one second.

2. formula for volume of a cylinder=area of cross section times length, and you have all the values you need
Area of cross section = Pi x radius squared (you are given diameter)
length is given in the diagram
3. (Original post by Stonebridge)
formula for volume of a cylinder=area of cross section times length, and you have all the values you need
Area of cross section = Pi x radius squared (you are given diameter)
length is given in the diagram
yeah, i got this far. but this just gives you the volume of the cylinder, but not the volume of air that passes in one second!
4. (Original post by Boomka)
yeah, i got this far. but this just gives you the volume of the cylinder, but not the volume of air that passes in one second!
In one tiny interval of time, a certain thin slice (a 2D circle) of air will pass by the turbine. If we increase the length of time to a whole second, the air passing the turbine will form a cylinder.

As posted above, the correct formula is

Area of cross section = Pi x radius squared (you are given diameter)

You then multiply this by the time (in this case, one second) to get the 'other' dimension and to turn the 2D circle in to a cylinder.
5. (Original post by M_E_X)
In one tiny interval of time, a certain thin slice (a 2D circle) of air will pass by the turbine. If we increase the length of time to a whole second, the air passing the turbine will form a cylinder.

As posted above, the correct formula is

Area of cross section = Pi x radius squared (you are given diameter)

You then multiply this by the time (in this case, one second) to get the 'other' dimension and to turn the 2D circle in to a cylinder.

ohh okay i see now! explanation with dimensions really helped to image the whole situation in my head thank you so much
6. (Original post by Boomka)
ohh okay i see now! explanation with dimensions really helped to image the whole situation in my head thank you so much
No problem
I'm doing physics at uni and had to write an essay on wind turbines T_T, so hopefully I know a bit about them .

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