Question

A body having moment of inertia of 2kgm^2 and rotating with an angular velocity
4 rads^-1 is slowed down to 2 rads^-1. What is the work done on the body?

Answer 1

Answer:

Use energy conservation

Work done is change in rotational energy

$W = \frac{1}{2} i { \omega_2}^{2} - \frac{1}{2} i { \omega_1}^{2} \\ \\ W= \frac{1}{2} \times 2 \times ( {2}^{2} - {4}^{2} ) = - 12 \: j$