What is the angular velocity of the tip of the blade?

Question

A gasoline-driven lawnmower has a blade that extends out 1.5 ft from its center. The tip of the blade is traveling at the speed of sound, which is 1,100 feet/sec.

 

5,254 rpm

 

7,006 rpm

733 rpm

 

21,019 rpm

Answer 1

The linear velocity is telling us how many circumferences the tip is traveling per second.

so 1100/2∏R = 116.71 = RPSecond.

116.71X60=7003 RPM the answer is the second one.