Q. A wheel of moment of inertia 2.5 Kg-$m^{2}$ has an initial angular velocity of 40 ${rads\ }^{- 1}$. A constant torque of 10 Nm acts on the wheel. The time during which the wheel is accelerated to 60 ${rads}^{- 1}$ is

A) 4 s
B) 6 s
C) 5 s
D) 2.5 s
Explanation

(c) Given, $MI = 2.5\ kgm^{- 2}$
$W = 40\ rad\ s^{- 1}$
$T = 10\ Nm$
As $T = I\alpha$
$10 = 2.5\alpha$
$\alpha = 4\ rad\ s^{- 2}$
Now, $\omega = \omega_{0} + \alpha t$
$60 = 40 + 4 \times t$
$20 = 4t$
$t = 5\ s$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.