Question

The angular speed of a fly-wheel making $120$ revolutions/minute is

• A. $4\pi rad/s$
• B. $4{\pi }^{2}rad/s$
• C. $\pi rad/s$
• D. $2\pi rad/s$

Answer 1

The correct option is A $4\pi rad/s$

Given $N=120$ revolutions /minute

$\Rightarrow$ Angular speed $=\frac{2\pi N}{60}=\frac{2\pi \times 120}{60}=4\pi$ $rad/s$