Question

A fly-wheel is rotating about its own axis at an angular velocity $11rad/s$. Its angular velocity in revolution per minute ($rpm$) is:

• A. $105$
• B. $210$
• C. $315$
• D. $420$

Answer 1

Answer: (A)

$105$

$\omega =11rad/s=2\pi n$

$\therefore$ $n=\frac{11}{2\pi }=\frac{11\times 7}{2\times 22}=\frac{7}{4}rps$$=\frac{7}{4}\times 60rpm=105rpm$