A ceiling fan rotates at $120$ rpm. Its angular speed is approximately:
A$12.6$ rad/s, since $\omega = 2\pi\cdot 2 = 4\pi$
B$120$ rad/s, the same as rpm in this case
C$2$ rad/s, simply $f$ in revolutions per second
D$60$ rad/s, half the rpm by convention
Answer & Solution
Correct answer: A. $12.6$ rad/s, since $\omega = 2\pi\cdot 2 = 4\pi$
$f = 120/60 = 2$ Hz, $\omega = 2\pi f = 4\pi \approx 12.57$ rad/s.