Calculate the rotational inertia for standard geometric shapes.
Geometric data
Results
Enter mass and relevant dimensions for the chosen shape
About this calculator
Overview
Mass moment of inertia (I) is the rotational analog of mass. It quantifies how much an object resists changes to its rotational motion about a specific axis. The distribution of mass far from the axis increases 'I' significantly.
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Pro Tips
SI units for moment of inertia are kg·m².
The location of the axis is critical; a rod has four times the inertia when rotated about its end compared to its center.
Objects with the same mass can have very different inertia values depending on their shape.
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Fun Facts
"A flywheel's ability to keep an engine running smoothly depends entirely on its high moment of inertia."
"Spacecraft use reaction wheels (spinning disks) to change their orientation without using fuel, by swapping angular momentum."
"Planets have different moments of inertia depending on their internal structure, which helps scientists understand their cores."
