Question

The moment of inertia of a flywheel having kinetic energy 1800J and angular speed of 30 radians/ sec is:

• A. $6kg{m}^2$
• B. $8kg{m}^2$
• C. $4kg{m}^2$
• D. $20kg{m}^2$

Answer 1

Answer: (C)

$4kg{m}^2$

The kinetic energy is given by $KE=I{\omega }^2/2⟹I=2KE/{\omega }^2$.
Substituting the values, we $I=2\times 1800/{30}^2=4kg-m^2$