Question

The angular speed of a flywheel making $120\text{revolutions /minute}$ is

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

Answer 1

The correct option is D $4\pi \text{rad/s}$

As we know, angular speed is given by
$\omega =\frac{2\pi n}{60}\text{rad/s}$, if $n$ is revolutions/min.
Here, it is given that $n=120$
$\therefore$ angular speed of flywheel is
$\omega =\frac{2\pi \times 120}{60}=4\pi \text{rad/s}$