A windmill for the generation of electric power has a propeller of diameter 1.8 m. In a wind of 40 km/h, this windmill delivers 200 W of electric power. (a) At this wind speed, what is the rate at which the air carries kinetic energy through the circular area swept out by the propeller? (The density of air is 1.29 kg/m3 ). (4 points) (b) What percentage of the kinetic energy of the air passing through this area is converted into electric energy?
Quanta , 7 Years ago
Grade 12th pass