Talk:Rigid body

message: I think that the problems of defining a relativistic version of the rigid body should be mentioned on this page.  Several paradoxes in relativity theory stem from this issue (e.g., the barn and pole-vaulter). Ty8inf (talk) 18:26, 7 April 2008 (UTC)
thread_title:  Relativity 

message: I believe that we need to introduce the terminology used in physics books. I mean: 
* linear position (or simply position) to indicate the position of a particle (center of mass, usually)
* angular position or orientation to indicate the orientation of a local basis set.
And take away the word displacement, as we already agreed. I do not agree that there is an urgent need to use a single word to say 
* "linear and angular position" or
* "position and orientation". 
Both expressions are correct, but too many people forget the first one. It is not too hard to use 3 or 4 words that have been used for centuries. And if I write "the position of this body is represented by a linear position vector and an orientation matrix" everybody should consider this terminology perfectly correct. I mean that too many people (mainly engineers) forget that the orientation is a position (notice that I am an engineer as well). 
Since we (I agree with you) don't like to define rigid body position using the concepts of (hypothetic) translation and rotation from reference position, I suggest another approach. See if you like my next edit, please. Paolo.dL (talk) 17:26, 28 August 2008 (UTC)
replies: text: I do like your edit.  There is not much I would change in it other than some personal wording preferences, which is not worth the effort.  Next up, let's tackle those kinematic equations by getting rid of the direction cosine matrices from the equations and making them basis-independent, and then introducing the concept of bases separately. MarcusMaximus (talk) 08:32, 30 August 2008 (UTC)
replies: text: OK, give me some time. I am busy right now, and I have to read again your previous comment, trying to understand exactly what you mean (notice that there was a discussion about the distinction between reference frames (RF) and coordinate systems (CS) in Talk:Frame of reference). Paolo.dL (talk) 09:31, 30 August 2008 (UTC)
thread_title:  Point 1 - Linear and angular position 

message: I was bold with my editing; I couldn't stand those clunky kinematical equations the way they were before.  I borrowed heavily from a textbook by Kane and Levinson called Online Dynamics, which is a self-guided computer course in dynamics.  There is certainly more to be done, like perhaps to add mathematical definitions of angular velocity and angular acceleration, or to give examples of how to use the many abstract equations I have just added.  I also want to improve the equation about "spatial acceleration" to make basis- and coordinate system-independent like the others, but it is not something I am familiar with. MarcusMaximus (talk) 08:34, 3 September 2008 (UTC)
replies: text: What you are trying to do is useful, but the article's structure was sound before your edits. Now parts are missing (we wrote that position and velocity are vector quantities, we did not write this for accelerations; you inserted addition theorems: why only for angular velocity and linear position?) and the order of the new paragraphs is not optimized. Wouldn't it be better for the readers to remove our latest edits, put them in a separate temporary page, and lock the article until you manage to obtain a completely new and publishable version of the article? I mean that an article, if possible, should not appear as a "work in progress". If it has reached a sound structure, that structure should not be substituted with another, unless the new one is equally sound, or at least reasonably sound. Paolo.dL (talk) 17:46, 4 September 2008 (UTC)
thread_title:  Kinematical equations, basis-independent 

message: It occurs to me that this page consists almost entirely of rigid body dynamics content.  There is little on this page that is not rigid body dynamics-related; possibly the section on geometry.  Shouldn't these two pages be merged, or at least move most of the content of this page to the other? MarcusMaximus (talk) 04:38, 11 September 2008 (UTC)
thread_title:  Merge with Rigid Body Dynamics? 

message: This article contradicts the following from the article on angular velocity: "In general, the angular velocity in an n-dimensional space is the time derivative of the angular displacement tensor which is a second rank skew-symmetric tensor". I'm assuming this quote is accurate, and this article is not. Can anyone verify this? 146.6.200.225 (talk) 20:44, 16 February 2010 (UTC)
thread_title:  angular velocity 

message: An interesting discussion about terminology is ongoing on Talk:Orientation (geometry)#Physical objects, bodies, figures, segments, spaces, planes, lines. In short, we all agree that unbounded lines or planes (in general N-D spaces) can be validly described as rigid collections of points. Can they be also validly called bodies? In other words, does it make sense to speak of a "body" of infinite size? 
IMPORTANT NOTE: If you are interested, please post your contribution there. Paolo.dL (talk) 11:55, 15 January 2011 (UTC)
thread_title:  Valid or invalid generalizations of the term "body" 

message: There was a page called rigid body motion which was a stub and now redirects here. There's also Euclidean group, which barely mentions SE(3). There is a page for rotation group, but none that get into the specific mathy details of SE(3) as a Lie algebra. I think that page needed. Does anyone mind if I start it back at rigid body motion with a DaB link here? —Ben FrantzDale (talk) 00:27, 25 May 2011 (UTC)
thread_title:  New page: Rigid-body motion? 

message: Refs 4,5,6,7 are either no longer available online or incorrectly cited. Is this a print textbook, an online course, or something else entirely? My interest is partly selfish - it looks like a rather useful reference and I would love to find it :). If it's an online course or textbook, a link would be useful. Thanks. 
128.32.240.58 (talk) 21:28, 7 June 2011 (UTC)
replies: text: I added those references.  It is a textbook that is only available in print, despite its title.  The same authors have published several fantastic textbooks that are available for free from Cornell University here:   The source I cited draws nearly all its material from those books.  It would probably be a good idea for me to go through and change the citations. MarcusMaximus (talk) 05:56, 8 June 2011 (UTC)
thread_title:  References?