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Power

http://filestore.aqa.org.uk/subjects/AQA-PHYA2-QP-JAN12.PDF
1BII?
Original post by Ayaz789


Hello there,

Here, the question is asking for the proportion of the total power that is contributed by the wind. In the previous question, you would have calculated the power that was developed by the sail (or in other words, provided by the wind). As the question has provided you with the other significant source of power and the magnitude of the power that it contributes, you can say that the percentage contribution is 100PwindPwind+Pengines\dfrac{100P_{wind}}{P_{wind} + P_{engines}}. Please ask if this needs to be clarified any further :smile:.
Reply 2
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Lychee628
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Original post by Smithenator5000
Hello there,

Here, the question is asking for the proportion of the total power that is contributed by the wind. In the previous question, you would have calculated the power that was developed by the sail (or in other words, provided by the wind). As the question has provided you with the other significant source of power and the magnitude of the power that it contributes, you can say that the percentage contribution is 100PwindPwind+Pengines\dfrac{100P_{wind}}{P_{wind} + P_{engines}}. Please ask if this needs to be clarified any further :smile:.

Okay so you basically did pwind/ (pwind and pengine) *100 for percentage!
Original post by Ayaz789
Okay so you basically did pwind/ (pwind and pengine) *100 for percentage!


Yes, that's right. You should get ~30% :smile: .
Reply 4
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Lychee628
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Original post by Smithenator5000
Yes, that's right. You should get ~30% :smile: .


Yep i have , thanks
Original post by Ayaz789
Yep i have , thanks


You're very welcome.
Reply 6
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Lychee628
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Original post by Smithenator5000
You're very welcome.


3bii?
Okay so i know cross sectional area is one but how can i explain it?
Original post by Ayaz789
3bii?
Okay so i know cross sectional area is one but how can i explain it?


Well, you can say that a larger cross-sectional area increases the number of air particles colliding with the craft as it travels. This means that the drag force for a particular velocity is going to be greater and thus the driving force and drag force balance at a lower velocity, a scenario in which the craft cannot accelerate any more.
(edited 7 years ago)
Reply 8
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Lychee628
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Original post by Smithenator5000
Well, you can say that a larger cross-section area increases the number of air particles colliding with the craft as it travels. This means that the drag force for a particular velocity is going to be greater and thus the driving force and drag force balance at a lower velocity, a scenario in which the craft cannot accelerate any more.


Ive only got 3 short lines to write on haha :smile: Maybe shorten it for me please?
Original post by Ayaz789
Ive only got 3 short lines to write on haha :smile: Maybe shorten it for me please?


Sorry, I was trying to be explicit. If I was going to write my answer in the exam . . .

"The cross-sectional area of the aircraft affects the maximum velocity. This is because it increases the air resistance experienced by it and thus means the driving force is balanced by drag at a lower velocity."

Concision was never my strong point :wink: .
Reply 10
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Lychee628
OP
19
Original post by Smithenator5000
Sorry, I was trying to be explicit. If I was going to write my answer in the exam . . .

"The cross-sectional area of the aircraft affects the maximum velocity. This is because it increases the air resistance experienced by it and thus means the driving force is balanced by drag at a lower velocity."

Concision was never my strong point :wink: .


Haha thanks :biggrin:
Original post by Ayaz789
Haha thanks :biggrin:


Once again, you're welcome. :smile:
sorry i just had to...

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