Calculating Moment of Inertia We have shown that for N discrete point masses distributed about a fixed axis the moment of inertia is Where ris the distance from the mass to the axis of rotation Example: Calculate the moment of inertia of four point masses (m)on the corners of a square whose sides have length L, about a perpendicular axis through the center of the square m m m m Physics 121: Lecture 18, Pg 5Physics 121: Lecture 18, Pg 5 Calculating Moment of Inertia We have shown that for N discrete point masses distributed about a fixed axis, the moment of inertia is: I = = m r i i i N 2 1 where r is the distance from the mass to the axis of rotation. Example: Calculate the moment of inertia of four point masses (m) on the corners of a square whose sides have length L, about a perpendicular axis through the center of the square: m m m m L