Power windmills turn in response to the force of high-speed drag. For a sphere moving through a fluid, the resistive force, FR i
s proportional to r 2 v 2 , where r is the radius of the sphere and v is the fluid speed. The power developed, P = FR v, is proportional to r 2 v 3 . The power developed by a windmill can be expressed as P = d r2 v 3 , where r is the windmill radius, v is the wind speed, and d = 4.3 W s3 /m5 . For comparison, a typical home needs about 3.0 kW of electric power. Note: This representation ignores system efficiency, which is about 25%. For a home windmill with a radius of 1.59 m, calculate the power delivered to the generator if the wind velocity is 12.4 m/s.\
