Question

The angular speed of a flywheel 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

Answer: (A)

4 $\pi$ rad/s

Answer 2

Number of revolutions per minute (n) = 120.
Therefore angular speed ( $\omega$)
= $\frac{ 2 \pi n}{ 60} = \frac{ 2 \pi \times 120}{ 60} = 4 \pi$ rad/s.