Mass moment of inertia of an Annulus
![annulus](../images/moment/di-cr.png)
Calculates the mass moment of inertia of an annulus or a disk with a hole.
`I_z = 1/2*m*(R^2+r^2)` (about central axis)
`I_x=I_y = 1/4*m*(R^2+r^2)` (about diameter)
Enter 'x' in the field to be calculated.
We use the following formulas to calculate the mass moment of inertia of an annulus (or disk with a hole) that has concentric outer and inner circles.
Case of a rotation about the disc central axis (z-axis on above diagram),
`I_z = 1/2*m * (R^2+r^2)`
Case of a rotation about a disc diameter (x-axis or y-axis on above diagram),
`I_x = I_y = 1/4*m * (R^2+r^2)`
m : mass of the annulus (kg)
R : annulus outer radius in meter (m)
r : annulus inner radius (or hole radius) in meter (m)
See also
Mass moment of inertia Calculators
Convert mass units
Convert distance units
Convert units of mass moment of inertia
Physics Calculators