Loading [MathJax]/extensions/tex2jax.js
User: No user logged in.


Steiner's Theorem

Storyboard

In general, moments of inertia are calculated with respect to axes that pass through the center of mass. However, in many situations rotation occurs around another axis. In that case, the moment of inertia on the throne of any parallel axis can be calculated based on the Steiner theorem, for which only the moment of inertia is needed with respect to the center of mass, the mass and the distance between the real axis and the one passes through the center of mass.

>Model

ID:(1456, 0)



Application of Steiner's theorem for a cylinder, $\parallel$ axis

Definition

For a cylinder with an axis parallel to the cylinder's own axis:



whose moment of inertia about the center of mass (CM) is given by

$ I_{CM} =\displaystyle\frac{1}{2} m r_c ^2$



the moment of inertia can be calculated using the Steiner's theorem with the following formula

$ I = I_{CM} + m d ^2$

.

ID:(11551, 0)



Application of Steiner's theorem for a cylinder, $\perp$ axis

Image

For a cylinder with an axis perpendicular to the cylinder's own axis:



whose moment of inertia about the center of mass (CM) is defined as

$ I_{CM} =\displaystyle\frac{1}{12} m ( h ^2+3 r_c ^2)$



the calculation of the moment of inertia can be carried out using the Steiner's theorem with the following formula

$ I = I_{CM} + m d ^2$

.

ID:(11552, 0)



Application of Steiner's theorem for a right parallelepiped

Note

For a right parallelepiped with an axis parallel to an edge:



whose moment of inertia about the center of mass (CM) is defined as

$ I_{CM} =\displaystyle\frac{1}{12} m ( a ^2+ b ^2)$



the calculation of the moment of inertia can be carried out using the Steiner's theorem with the following formula

$ I = I_{CM} + m d ^2$

.

ID:(11554, 0)



Application of Steiner's theorem to a sphere

Quote

For a sphere with an axis at a distance from its center:



whose moment of inertia about the center of mass (CM) is defined as

$ I_{CM} =\displaystyle\frac{2}{5} m r_e ^2$



the calculation of the moment of inertia can be carried out using the Steiner's theorem with the following formula

$ I = I_{CM} + m d ^2$

.

ID:(11553, 0)



Steiner's Theorem

Storyboard

In general, moments of inertia are calculated with respect to axes that pass through the center of mass. However, in many situations rotation occurs around another axis. In that case, the moment of inertia on the throne of any parallel axis can be calculated based on the Steiner theorem, for which only the moment of inertia is needed with respect to the center of mass, the mass and the distance between the real axis and the one passes through the center of mass.

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$m$
m
Body mass
kg
$d$
d
Distance Center of Mass and Axis
m
$I$
I
Moment of inertia for axis that does not pass through the CM
kg m^2
$I_{CM}$
I_CM
Moment of Inertia Mass Center
kg m^2

Calculations


First, select the equation:   to ,  then, select the variable:   to 
I = I_CM + m * d ^ 2mdII_CM

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

 Variable   Given   Calculate   Target :   Equation   To be used
I = I_CM + m * d ^ 2mdII_CM



Equations


Examples

The moment of inertia for axis that does not pass through the CM ($I$) can be calculated using the moment of Inertia Mass Center ($I_{CM}$) and adding the moment of inertia of the body mass ($m$) as if it were a point mass at the distance Center of Mass and Axis ($d$):

kyon

For a cylinder with an axis parallel to the cylinder's own axis:

image



whose moment of inertia about the center of mass (CM) is given by list=4434

equation=4434



the moment of inertia can be calculated using the Steiner's theorem with the following formula list=3688

equation=3688.

For a cylinder with an axis perpendicular to the cylinder's own axis:

image



whose moment of inertia about the center of mass (CM) is defined as list=4435

equation=4435



the calculation of the moment of inertia can be carried out using the Steiner's theorem with the following formula list=3688

equation=3688.

For a right parallelepiped with an axis parallel to an edge:

image



whose moment of inertia about the center of mass (CM) is defined as list=4433

equation=4433



the calculation of the moment of inertia can be carried out using the Steiner's theorem with the following formula list=3688

equation=3688.

For a sphere with an axis at a distance from its center:

image



whose moment of inertia about the center of mass (CM) is defined as list=4436

equation=4436



the calculation of the moment of inertia can be carried out using the Steiner's theorem with the following formula list=3688

equation=3688.


>Model

ID:(1456, 0)