another question.......

let in time dt, (dx*A) volume of air crosses blades where A is area of face of windmill. So mass of air crossing windmill per unit time = A(dx/dt)=Av. also energy of wind converted 2 power is proprtional to energy of wind 1/2mv²*mass of wind crossing per unit time i.e. Av

therefore proportional to v³

but only one thing power generated is propotional to K.E?

great abhisekh! thank you..