Elysian Shadows

I can't seem to understand that so i would greatly appreciate any help.

Velocity of a Lawnmower Blade A gasoline-driven lawnmower has a blade that extends out 1 foot from its center. The tip of the blade is traveling at the speed of sound, which is 1,100 feet per second. Through how many revolutions per minute is the blade turning?

Um, I think it should be:

Your radius: 1 foot ( x 2 = Diameter: 2 feet)
Your circumference: 6.28 ft (2 x pi)
Speed: 1,100 f/s (66,000 f/m)

So your speed in feet per minute (above) divided by the number of feet per revolution (circumference) should be the answer.

66,000/6.28 = 10,509.554 revolutions per minute

I think anyway.. it's been a while, heh.

Thank you so much haha i kinda spaced on that problem. Guess i was complicating the problem more then i should have.