Moment of Inertia of a Sphere Formula, Solid Sphere |
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I=25⋅m⋅r2 | ||
Symbol | English | Metric |
I = Moment of Inertia | lbm/ft2−sec | kg/m2 |
m = Mass | lbm | kg |
r = Radius | in | mm |
This calculation is for the moment of inertia of a sphere. There are three separate calculations: a solid sphere, a hollow sphere and a hollow core sphere. The difference between a hollow sphere and a hollow core sphere is a hollow sphere has a thin shell, or a thickness that is neglible. Because a sphere is the same dimensions in every dimension, the moment of inertia is the same about every axis.
Moment of Inertia of a Sphere Formula, Hollow Sphere |
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I=23⋅m⋅r2 | ||
Symbol | English | Metric |
I = Moment of Inertia | lbm/ft2−sec | kg/m2 |
m = Mass | lbm | kg |
r = Radius | in | mm |
Moment of Inertia of a Sphere Formula, Hollow Core Sphere |
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I=25⋅m⋅r2⋅r52−r51r32−r31 | ||
Symbol | English | Metric |
I = Moment of Inertia | lbm/ft2−sec | kg/m2 |
m = Mass | lbm | kg |
r = Radius | in | mm |
r1 = Radius | in | mm |
r2 = Radius | in | mm |