On a calm day with no wind, you can run a 1500-m race at a velocity of 4.0 m/s. If you run the same race on a day when you have
2 answers:
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Answer:
a) 5.22 m/s
b) 31.4 %
Explanation:
f = rotating speed = 15 rpm = 15/60 =0.25 rps
m = Mass flow rate of air = 42000 kg/s
v = Tip velocity = 250 km/h = 250/3.6 = 69.44 m/s
W = Work output = 180 kW
A = Swept area of wind turbine
r = Radius of wind turbine
η = Efficiency
∴ The average velocity of the air is 5.22 m/s
∴ Conversion efficiency of the turbine is 0.314 or 31.4 %