Definition:Moment of Inertia/Discrete

Definition

Let $B$ be a rigid body which is rotating in space about some axis $\LL$.

Let $B$ be composed of a countable number of particles $P_1, P_2, \ldots$ such that:

each $P_i$ has mass $m_i$

each $P_i$ has perpendicular distance $r_i$ from $\LL$.

The moment of inertia of $B$ about $\LL$ is given by:

$I := \ds \sum m_i {r_i}^2$

Also see

• Results about moment of inertia can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): moment of inertia
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): moment of inertia