Q. A wheel of moment of inertia $5 \times 10^{- 3}kg - m^{2}$ is making 20 revolutions per second. It is stopped in 20 seconds, then the angular retardation is
A) $\pi\ radian/sec^{2}$
B) $2\pi\ radian/sec^{2}$
C) $4\pi\ radian/sec^{2}$
D) $8\pi\ radian/sec^{2}$
Explanation
(b) $n_{1} = 20\ rev/s,n_{2} = 0,\ t = 20s$
$\alpha = \frac{2\pi(n_{2} - n_{1})}{t} = - \frac{2\pi \times 20}{20} = - 2\pi\ rad/s^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.