Answer
(a) $753.98 $ radian per minute
(b) $12063.7$ ft/min
Work Step by Step
(a) The length of the rotor blade is the radius $r=16ft$, and the frequency $f=120rpm$
The angular speed $\omega$ of the rotor is give by $\omega=2\pi f=240\pi\approx753.98 $ radian per minute
(b) The linear speed $v$ of a point on the tip of a blade is given by $v=r\omega=16\times240\pi\approx12063.7$ ft/min (about 137 mile/hour)
