I'm a HS sophomore, and I am hoping to become an engineer of some sort someday. I'm working on a homework problem which I can't seem to solve. I'll post the question and how I went about trying to solve it. Please let me know if I've done anything wrong.
"Assume a wind turbine with a hub 50 m above ground, a rotor diameter of 25 m and a wind-conversion efficientcy of 25%. The turbine will operate in an area w/ an average windpower density of 600 watts per square meter at 50m altitude. How many kwh can the turbine generate per year?"
I started out by using pi x r^2
pi x (12.5)^2=490.8738521 square meters
then I multiplied by .25 (the efficiency) and multiplied by 600.
That gives me 73631.07782 watts, which equals 73.632 Kilwatts
I've been told that 73.632 is incorrect... why?