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Document Title
Fundamentals of Stress and Vibration 2. Engineering Mechanics Chapter
[A Practical guide for aspiring Designers / Analysts]

Situation 5: find the mass moment of inertia of a cylinder about a vertical axis perpendicular to
the axis of the cylinder, as shown in [Fig 2.31].

[Fig 2.31: Thick cylinder rotating about an axis of symmetry
perpendicular axis of the cylinder]

Solution 5 the mass moment of inertia about the vertical axis has two components:

1) Inertia about the axis of rotation (treating the elemental section on the cylinder as a point
mass)
2) Inertia about the vertical axes of the elemental sections themselves. Therefore, from
[Fig 2.32] we have the total MMOI of the cylinder about the vertical axis of symmetry to be:

[Fig 2.32: Rotation of an elemental section about its vertical diameter]

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