Question

A ring of radius 0.5 m and mass 10 kg is rotating about its diameter with angular velocity of `20 rad s^(-1)`. Its kinetic energy is
A. 10 J
B. 100 J
C. 500 J
D. 250 J

Answer 1

Correct Answer - D
Moment of inertia of a ring about its diameter `I = (1)/(2)mr^(2)` and kinetic energy is given by
`E_(k)=(1)/(2)I omega^(2)rArr E_(k)=(1)/(4)mr^(2)omega^(2)=(1)/(4)xx10xx(0.5)^(2)xx(20)^(2)=250 J`.