Physics - Rotation Question with Solution | TestHub

Initial angular velocity, ${\omega }_0=600\text{ rpm}=\frac{600\times 2\pi }{60}\text{ rad/s}=20\pi \text{ rad/s}$

Final angular velocity, $\omega =0$

Time taken to come to rest, $t=30\text{ s}$

Using the equation of kinematics for rotational motion, $\omega ={\omega }_0+\alpha t$

$0=20\pi +\alpha (30)$

$\alpha =-\frac{2\pi }{3}{\text{ rad/s}}^2$

The angular retardation is $\frac{2\pi }{3}{\text{ rad/s}}^2$.

Answer: $\frac{2\pi }{3}$