Moment of Inertia

Rotational Kinetic Energy :

Derived from Linear Kinetic energy :

EK = 1/2 mv^2 = 1/2 [m(r^2)](w^2) ------------> angular speed does not change within whole rigid body
Moment of Inertia is defined as
I = mr^2

MIT OCW Walter Lewin 8.01 L03 Fall 1999

Two Shortcuts to ease the finding of Moment of Inertia of an object

1) plugin another axis and I = Icenter + m d^2 where d is the distance between the center axis and the plugged axis

2)

Rotational Kinetic Energy can be stored in flying wheel for coverting into useful forms of energy when applicable. Eg : Toy cars, Neutron Star, earth, huge flying wheel in MIT magnetic labs