Wind blows steadily at 7 m/s at a site. For a wind turbine with 80-m-diameter blades, determine (a) the mechanical energy of the air per unit mass (in J/kg), (b) the power-generation potential (in MW), and (c) the actual electric power output if the overall efficiency is 30 percent (in MW). Take the air density as 1.25 kg/m^{3}.