RPM of a Lawnmower, given radius, speed of blade

[Sid]

I have a trig questions that asks what the RPM of a lawnmower blade is if the radius equals 1 and the speed of the blade is 1100 feet per sec. So far I have come up with (want to see if this is correct)

one revolution = 2pie radians(R x Pie)

So I converted feet per second into feet per minute

66000 feet per min by 6.283 (2pie radians) and came up with: 10504 rpm.

Can anyone verify that I did this correct?

Many thanks!
-Sid

 

[stapel]

Do you mean "the speed of the tip of the blade", perhaps?

Thank you.

Eliz.

P.S. "Pie" is a pastry confection; "pi" is a number.

 

[Sid]

Sorry... yes the tip of the blade travels at 1100 feet per second.

 

[stapel]

And do you mean that "the radius of the blade is one foot"? (Your book really should have written the exercise more completely, so that we wouldn't have to be making so many guesses.)

If so, then your answer is (approximately) correct. (The exercise doesn't seem to state whether the answer should be approximate, rounded to some degree of accuracy, or exact.)

Eliz.