Convergence problem: Difference between revisions
Jump to navigation
Jump to search
en>Brad7777 →References: removed catgeory mathematical analysis |
en>Xnn remove opinion |
||
| Line 1: | Line 1: | ||
The following is a list of [[second moment of area|area moments of inertia]]. The area moment of inertia or [[second moment of area]] has a [[physical unit|unit]] of dimension length<sup>4</sup>, and should not be confused with the [[mass moment of inertia]]. If the piece is thin, however, the mass moment of inertia equals the area density times the area moment of inertia. Each is with respect to a horizontal axis through the [[centroid]] of the given shape, unless otherwise specified. | |||
==Area moments of inertia== | |||
{|class="wikitable" | |||
|- | |||
! Description || Figure || Area moment of inertia || Comment || Reference | |||
|- | |||
| a filled circular area of radius ''r''||[[Image:Area moment of inertia of a circle.svg]]||<math>I_0 = \frac{\pi}{4} r^4</math>|| ||<ref>{{cite web|url=http://www.efunda.com/math/areas/Circle.cfm|title=Circle|accessdate=2006-12-30|publisher=eFunda}}</ref> | |||
|- | |||
| an [[annulus (mathematics)|annulus]] of inner radius''r''<sub>1</sub> and outer radius''r''<sub>2</sub>||[[Image:Area moment of inertia of a circular area.svg]]||<math>I_0 = \frac{\pi}{4} \left({r_2}^4-{r_1}^4\right)</math>|| For thin tubes, this is approximately equal to: <math>\pi \left(\frac{{r_2}+{r_1}}{2}\right)^3 \left({r_2}-{r_1}\right)</math> or <math>\pi {r}^3{t}</math> .|| | |||
|- | |||
| a filled [[circular sector]] of angle ''θ'' in [[radian]]s and radius ''r'' with respect to an axis through the centroid of the sector and the center of the circle||[[Image:Area moment of inertia of a circular sector.svg]]||<math>I_0 = \left( \theta -\sin \theta \right) \frac{r^{4}}{8}</math>||This formula is valid for only for 0 ≤ <math>\theta</math> ≤ <math>\pi</math> || | |||
|- | |||
| a filled semicircle with radius ''r'' with respect to a horizontal line passing through the centroid of the area||[[Image:Area moment of inertia of a semicircle 2.svg]]||<math>I_0 = \left(\frac{\pi}{8} - \frac{8}{9\pi}\right)r^4 \approx 0.1098r^4 </math>|| ||<ref name=semicircle>{{cite web|url=http://www.efunda.com/math/areas/CircleHalf.cfm|title=Circular Half|accessdate=2006-12-30|publisher=eFunda}}</ref> | |||
|- | |||
| a filled semicircle as above but with respect to an axis collinear with the base||[[Image:Area moment of inertia of a semicircle.svg]]||<math>I = \frac{\pi r^4}{8}</math>||This is a consequence of the [[parallel axis theorem]] and the fact that the distance between these two axes is <math>\frac{4r}{3\pi}</math>||<ref name=semicircle /> | |||
|- | |||
| a filled semicircle as above but with respect to a vertical axis through the centroid||<center>[[Image:Area moment of inertia of a semicircle 3.svg]]</center>||<math>I_0 = \frac{\pi r^4}{8}</math>|| ||<ref name=semicircle /> | |||
|- | |||
| a filled quarter circle with radius ''r'' entirely in the 1st quadrant of the [[Cartesian coordinate system]]||[[Image:Area moment of inertia of a quartercircle.svg]]||<math>I = \frac{\pi r^4}{16}</math>|| ||<ref name=quartercircle>{{cite web|url=http://www.efunda.com/math/areas/CircleQuarter.cfm|title=Quarter Circle|accessdate=2006-12-30|publisher=eFunda}}</ref> | |||
|- | |||
| a filled quarter circle as above but with respect to a horizontal or vertical axis through the centroid||[[Image:Area moment of inertia of a quartercircle 2.svg]]||<math>I_0 = \left(\frac{\pi}{16}-\frac{4}{9\pi}\right)r^4</math>||This is a consequence of the [[parallel axis theorem]] and the fact that the distance between these two axes is <math>\frac{4r}{3\pi}</math> ||<ref name=quartercircle /> | |||
|- | |||
| a filled [[ellipse]] whose radius along the ''x''-axis is ''a'' and whose radius along the ''y''-axis is ''b''||[[Image:Area moment of inertia of an ellipsis.svg]]</td><td><math>I_0 = \frac{\pi}{4} ab^3</math>|| || | |||
|- | |||
| a filled rectangular area with a base width of ''b'' and height ''h''||[[Image:Area moment of inertia of a rectangle.svg]]||<math>I_0 = \frac{bh^3}{12}</math>|| ||<ref name=rect>{{cite web|url=http://www.efunda.com/math/areas/rectangle.cfm|title=Rectangular area|accessdate=2006-12-30|publisher=eFunda}}</ref> | |||
|- | |||
| a filled rectangular area as above but with respect to an axis collinear with the base||[[Image:Area moment of inertia of a rectangle 2.svg]]||<math>I = \frac{bh^3}{3}</math>||This is a result from the [[parallel axis theorem]]||<ref name=rect /> | |||
|- | |||
| a filled rectangular area as above but with respect to an axis collinear, where ''r'' is the perpendicular distance from the centroid of the rectangle to the axis of interest|| ||<math>I = \frac{bh^3}{12}+bhr^2</math>||This is a result from the [[parallel axis theorem]]||<ref name=rect /> | |||
|- | |||
| a filled triangular area with a base width of ''b'' and height ''h'' with respect to an axis through the centroid||[[Image:Area moment of inertia of a triangle.svg]]||<math>I_0 = \frac{bh^3}{36}</math>|| ||<ref name=tri>{{cite web|url=http://www.efunda.com/math/areas/triangle.cfm|title=Triangular area|accessdate=2006-12-30|publisher=eFunda}}</ref> | |||
|- | |||
| a filled triangular area as above but with respect to an axis collinear with the base||[[Image:Area moment of inertia of a triangle 2.svg]]||<math>I = \frac{bh^3}{12}</math>||This is a consequence of the [[parallel axis theorem]] ||<ref name=tri /> | |||
|- | |||
| a filled [[regular hexagon]] with a side length of ''a''||[[Image:Area moment of inertia of a regular hexagon.svg]]||<math>I_0 = \frac{5\sqrt{3}}{16}a^4</math>||The result is valid for both a horizontal and a vertical axis through the centroid, and therefore is also valid for an axis with arbitrary direction that passes through the origin.|| | |||
| | |||
|- | |||
| Any plane region with a known area moment of inertia for a parallel axis. (Main Article [[parallel axis theorem]]) ||[[Image:Parallel Axes Compact.png]]||<math>I_z = I_x + Ar^2</math> || This can be used to determine the second moment of area of a rigid body about any axis, given the body's moment of inertia about a parallel axis through the object's center of mass and the perpendicular distance (r) between the axes. | |||
|} | |||
==See also== | |||
* [[List of moments of inertia]] | |||
==References== | |||
{{reflist}} | |||
==External links== | |||
* [http://www.amesweb.info/SectionalPropertiesTabs/SectionalProperties.aspx Online Sectional Properties Calculator] | |||
* [http://civilengineer.webinfolist.com/str/micalc.htm Online Calculator for Area Moment of Inertia ] | |||
[[Category:Mechanics|Area moment of inertia]] | |||
[[Category:Physics-related lists|Area moments of inertia]] | |||
Revision as of 18:07, 12 March 2013
The following is a list of area moments of inertia. The area moment of inertia or second moment of area has a unit of dimension length4, and should not be confused with the mass moment of inertia. If the piece is thin, however, the mass moment of inertia equals the area density times the area moment of inertia. Each is with respect to a horizontal axis through the centroid of the given shape, unless otherwise specified.
Area moments of inertia
| Description | Figure | Area moment of inertia | Comment | Reference | |
|---|---|---|---|---|---|
| a filled circular area of radius r | File:Area moment of inertia of a circle.svg | [1] | |||
| an annulus of inner radiusr1 and outer radiusr2 | File:Area moment of inertia of a circular area.svg | For thin tubes, this is approximately equal to: or . | |||
| a filled circular sector of angle θ in radians and radius r with respect to an axis through the centroid of the sector and the center of the circle | File:Area moment of inertia of a circular sector.svg | This formula is valid for only for 0 ≤ ≤ | |||
| a filled semicircle with radius r with respect to a horizontal line passing through the centroid of the area | File:Area moment of inertia of a semicircle 2.svg | [2] | |||
| a filled semicircle as above but with respect to an axis collinear with the base | File:Area moment of inertia of a semicircle.svg | This is a consequence of the parallel axis theorem and the fact that the distance between these two axes is | [2] | ||
| a filled semicircle as above but with respect to a vertical axis through the centroid | [2] | ||||
| a filled quarter circle with radius r entirely in the 1st quadrant of the Cartesian coordinate system | File:Area moment of inertia of a quartercircle.svg | [3] | |||
| a filled quarter circle as above but with respect to a horizontal or vertical axis through the centroid | File:Area moment of inertia of a quartercircle 2.svg | This is a consequence of the parallel axis theorem and the fact that the distance between these two axes is | [3] | ||
| a filled ellipse whose radius along the x-axis is a and whose radius along the y-axis is b | File:Area moment of inertia of an ellipsis.svg | ||||
| a filled rectangular area with a base width of b and height h | File:Area moment of inertia of a rectangle.svg | [4] | |||
| a filled rectangular area as above but with respect to an axis collinear with the base | File:Area moment of inertia of a rectangle 2.svg | This is a result from the parallel axis theorem | [4] | ||
| a filled rectangular area as above but with respect to an axis collinear, where r is the perpendicular distance from the centroid of the rectangle to the axis of interest | This is a result from the parallel axis theorem | [4] | |||
| a filled triangular area with a base width of b and height h with respect to an axis through the centroid | File:Area moment of inertia of a triangle.svg | [5] | |||
| a filled triangular area as above but with respect to an axis collinear with the base | File:Area moment of inertia of a triangle 2.svg | This is a consequence of the parallel axis theorem | [5] | ||
| a filled regular hexagon with a side length of a | File:Area moment of inertia of a regular hexagon.svg | The result is valid for both a horizontal and a vertical axis through the centroid, and therefore is also valid for an axis with arbitrary direction that passes through the origin. | |||
| Any plane region with a known area moment of inertia for a parallel axis. (Main Article parallel axis theorem) | File:Parallel Axes Compact.png | This can be used to determine the second moment of area of a rigid body about any axis, given the body's moment of inertia about a parallel axis through the object's center of mass and the perpendicular distance (r) between the axes. |
See also
References
43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.