Q. A wheel has a speed of 1200 revolutions per $minute$ and is made to slow down at a rate of $4\ radians/s^{2}$. The number of revolutions it makes before coming to rest is
A) 143
B) 272
C) 314
D) 722
Explanation
(c) $\omega^{2} = \omega_{0}^{2} - 2\alpha\theta \Rightarrow 0 = 4\pi^{2}n^{2} - 2\alpha\theta$
$\theta = \frac{4\pi^{2}\left( \frac{1200}{60} \right)^{2}}{2 \times 4} = 200\pi^{2}rad$
$\therefore 2\pi n = 200\pi^{2} \Rightarrow n = 100\pi = 314$ revolution
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.