A Wheel is rotating at 1800 rpm about its own axis when the power is switched off, it comes to rest

Question

A Wheel is rotating at 1800 rpm about its own axis when the power is switched off, it comes to rest in 2 minutes. Then the angular retardation in $\operatorname{rads}^{-2}$ is\

Professor PC Thomas Classes · Answer

Here Initial angular speed, $\omega_{0}=\frac{2 \pi 	imes 1800}{60} \mathrm{rads}^{-1}$\ $=60 \pi \mathrm{rad} \mathrm{s}^{-1}$\ Final angular speed,\ $\omega=0$ (s wheel comes to rest)\ Time, $\mathrm{t}=2$ minutes $=120 \mathrm{~s}$\ $	herefore$ Angular retardation $=\frac{\omega_{0}-\omega}{\mathrm{t}}$\ $=\frac{60 \pi-0}{120}=\frac{\pi}{2} \mathrm{rads}^{-2}$\