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Bertz law math problem

  1. Oct 20, 2013 #1
    1. The problem statement, all variables and given/known data

    The density of air under normal conditions is about 1.2 kg/m^3. For a wind speed of 10 m/s find

    a) the actual power carried by the wind

    b) the maximum possible power (Bert'z limit) extractable by a wind turbine with a blade area of 10 m^2 and

    c) the actual power extracted by a wind turbine with a blade area of 10 m^2 and a power coefficient of 0.46

    2. Relevant equations

    Maximum extractable wind power = 2a(1-a)^2pv^3

    The maximum extractable power is 59%

    Total wind power= 1/2pv^3

    3. The attempt at a solution

    A) total wind= 1/2 (1.2 kg/m^3)(10m/s)^3
    = 600W

    B) I would use the formula 2a(1-a)^2pv^3

    but how do I know what a is?

    I'm not sure if I did part a right and am confused on part b
  2. jcsd
  3. Oct 21, 2013 #2
    Can someone please help me with part B?
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