User:Brews ohare/Sandbox5

The following RfC was filed:

RfC: Is the following example a useful contribution to Centrifugal force (rotating reference frame)?

Is the following example a useful addition to the subsection Apparent motion of stationary objects?

Objections have been raised regarding an example, suggesting that it is WP:OR. The example is provided at this link. Please comment upon its suitability and, if possible, provide suggestions for its improvement. Brews ohare (talk) 21:00, 6 August 2010 (UTC)

• Here is the example:

Dropping bird

A bird moving vertically parallel to the axis of rotation in a rotating frame appears to spiral downward in the inertial frame. The bird begins the drop with a horizontal component of velocity the same as the target site. The left panel shows a downward view in the inertial frame. The rate of rotation |Ω| = ω is assumed constant in time.

Let's look at a straight-line motion as seen in a rotating frame, rather than in one that is stationary. To be concrete, imagine a bird dropping onto a carousel, represented as a rotating flat platform. The figure shows the vertical straight-line path of descent seen in the rotating frame. The bird drops at constant speed, occupying successively the vertically aligned positions one, two, three. Because the bird has zero horizontal velocity from the viewpoint of the rotating observer on the carousel, there is no Coriolis force in this example. There is, however, a centrifugal force.

In the stationary frame, however, the bird descends on the spiral path shown in the figure, because the target position on the carousel is rotating. The stationary observer sees a uniform circular motion of the bird when the spiral motion is projected downward, as in the left panel of the figure.

The stationary observer and the observer on the rotating carousel agree that there is no vertical force involved: the bird travels vertically at constant speed.

The horizontal motion is seen differently by the two observers. The rotating observer always sees a centrifugal force that tends to carry the bird away. It must be counteracted by a radial thrust to prevent a landing far off the mark. In contrast, the stationary observer, looking at the circular motion in the horizontal plane at the left of the figure, sees a centripetal force is necessary. Without a radial thrust, the bird would follow the dashed vertical path in the left panel of the figure, obeying Newton's law of inertia.

Unlike the dropping ball case, where the fictitious Coriolis and centrifugal forces added together to produce the force necessary for the motion so there was no need for external agency, in this case the fictitious forces create a need for intervention. The basic rule is: if the inertial observer finds a situation demands action, the fictitious forces of the rotational frame will lead the rotational observer to the same conclusion, albeit by a different mechanism.

References

Subsequently a much briefer and less specific discussion was made.

To both the accusation of WP:OR was filed. All efforts to solicit a clarification of that judgment failed to produce any attempt at clarification, and in fact, instead, it was suggested that it was disruptive to ask for clarification.

Original research - revisited again

Please stop. If you continue to violate Wikipedia's no original research policy by adding your personal analysis or synthesis into articles, you may be blocked from editing Wikipedia. Please don't add original research to articles as you did with this edit on Centrifugal force (rotating reference frame), and as you did before with this edit on the same page, and with this string of edits on Redefinition of the metre in 1983. I have removed the section and left a note on the talk page. Thank you. DVdm (talk) 20:45, 8 August 2010 (UTC)

Polite requests for elucidation led to abuse.

Blackburne: OK, let's look at this in detail to assist you in becoming specific. Let's ask: What needs to be sourced?

• The first four paragraphs are simply describing the situation to be examined, setting up the discussion. As simply a set-up describing what is to be discussed, that hardly needs to be sourced.
• The statement about no vertical force can be sourced to Newton's law F=ma if you really need that.
• The next paragraph describes the horizontal motion in the rotating frame. There isn't any. I don't think we need a source here, that is simply the description of the vertical path.
• The assertion is made that there is a centrifugal force present in the rotating frame. That can be sourced if you insist, but of course that is the entire subject of this article and so hardly requires a new source. Rotating frames always have centrifugal force.
• The second from last paragraph describes the projection of a spiral path on the horizontal plane as a circular arc. I believe that to be an obvious point: do you want a source describing projection of a spiral down a cylinder as a circle in plane perpendicular to the cylinder?
• The next statement is that circular motion implies a centripetal force. Again, this connection is clear; a link to Centripetal force can be provided if you wish.
• The last paragraph is a summary.

Please go down this list and suggest where you have dissatisfaction. So far as I can see, there is nothing here of such import as to require an OR label or extensive sourcing. I find myself perplexed trying to understand specifically what you object to. Please try to clarify. Brews ohare (talk) 14:49, 7 August 2010 (UTC)

BTW, this RfC was introduced at the request of DVdm, who felt some additional input would be helpful. Please avoid maneuvering to create the appearance of disruption. Brews ohare (talk) 15:13, 7 August 2010 (UTC)

John Blackburne: Let's divide this question into three parts.

Part 1: Putting aside all WP policies, do you personally think there is anything debatable about the section Straight-line motions? I know your personal beliefs are not pertinent to WP, but I'd like to know your position: do you have to be persuaded, or are you in agreement yourself, personally?

Part 2: Do you believe that all material, even completely uncontroversial and correct material that raises questions from nobody, must be sourced to avoid violation of WP:OR?

Part 3: Do you believe that the sections listed earlier meet your criteria, or are they also in violation of WP:OR?

My feeling is that item 2 is too stringent and that the sections listed in item 3 must be taken as in violation of WP:OR if item 2 is the criterion. Brews ohare (talk) 23:17, 8 August 2010 (UTC)

Brews, stop it. As it clearly says at WP:DISRUPTPOINT,

• If you think someone unjustifiably removed "unsourced" content...
  • do find a source for it, make the referencing clear if it was already present, or explain why the content in question shouldn't require a cited source
  • do not remove all apparently unsourced content on the page

So no, this is not about the other content on the page, stop trying to disrupt this talk page by trying to draw us into debating the whole page or into a debate about policy. Just properly source your contributions.--JohnBlackburne^words_deeds 00:44, 9 August 2010 (UTC)