Yeah, I although "moment of inertia" does not include everything that is related to the term. Adding term "polar" increases comprehensibility a lot. I do know what it's about, the english term just confused me a bit. Letter "J" I know better than I would like.

Also, what you posted is rotational energy of a rigid body. It's related to momentum, but it's not the same thing... I trust you know that?
Linear momentum is
p=mv and similarly angular momentum is
L = Jω = M dtin which
J is analogous to mass
m and
ω (angular velocity) is analogous to velocity v.
J is derived from the mass and shape of the body. Alternatively, L can be defined via momentum (M) gained in a time (dt) (momentum being calculated by simply M =
r x
F), but in this case it's rather called impulse momentum and it implies a change in the rotational momentum L.
Rotational energy and linear kinetic energy are also related to momentum, as
Ek=kinetic energy, Er=rotational energy
Ek = Integral p dv = Integral (mv) dv = ½ m v^2 + C
Er= Integral L dω = Integral (Jω) dω = ½ J ω^2 + C
If v and ω are constant (as they are in one given moment), C = 0 in both cases, giving the familiar equations for both linear kinetic energy and rotational energy.
