The blades of a windmill sweep out a circle of area A. (a) If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time t? (b) What is the kinetic energy of the air? (c) Assume that the windmill converts 25% of the wind’s energy into electrical energy, and that A = 30 m2, v = 36 km/h and the density of air is 1.2 kg m-3 . What is the electrical power produced?

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m*(kg/sec)= (density of air )x Axv where v=36 km/h = 10m/s m*= 360kg/sec let unit of time 't' is in Second mass = 360t kg kinetic energy = .5x (density of air)x(swept area of windmill)x(velocity of air)³ K.E.= 18000 jule/sec power produced = .25x 18000= 4500 jule/sec
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m*(kg/sec)= (density of air )x Axv where v=36 km/h = 10m/s m*= 360kg/sec let unit of time 't' is in Second mass = 360t kg kinetic energy = .5x (density of air)x(swept area of windmill)x(velocity of air)³ K.E.= 18000 jule/sec power produced = .25x 18000= 4500 jule/sec read less
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