Erm, man the windmill question was a little depressing
Anyway, what I did was.. erm
It's hard to recollect
I guess there was a question before the one where we had to find the mass, where they asked us to find out the power... shwoing all your calculations
Using the efficiency percentage they gave as 10%, I calculated the Energy as 54,000 Joules.
THEN, the E=Pt P= E divided by T. 54000/1 = 54,000 W (watts)
Then, erm, I was really confused for the next one.
I thought about using the Energy formula itself like KE= 0.5 mv
2but then i thought.. if the velocity is halved, how would the mass increase
cuz technically if the velocity decreased, then the mass of air passing through the turbines should fall...
... So I just used a ratio and got an answer I can't seem to remember
BUT I think I'm wrong. As they said earlier, probably a heavier mass would mean that speed has decreased
BUT I DID get the fraction as 1/8... These two answers were really difficult