Talk:Newton's cradle

message: This article could really do with an explanation of the physics behind this. The first sentence mentions stuff like conservation of momentum and energy, but that doesn't really help to explain how this device works to the layman. I'd write it myself, but I don't know how it works. =P – Lantoka (talk) 03:54, 12 February 2007 (UTC)
thread_title:  Explanation of the Physics? 

message: Am I the only one who finds the elastic collision animation so distracting it's almost impossible to read the article? That and many other highly distracting gifs are already on the elastic collision page. Do we really need it here? Kafziel Talk 16:17, 28 February 2007 (UTC)
replies: text: In particular, the bright green backgrounds are distracting and unnecessary. White or grey would be less intrusive, as shown by the 3d animations. 173.172.70.38 (talk) 19:28, 17 March 2014 (UTC)
thread_title:  Elastic collision 

message: Other names for this are:
    Collision Apparatus
        http://physics.kenyon.edu/EarlyApparatus/Mechanics/Collision_Apparatus/Collision_Apparatus.html
    "Balance Balls", "Newton's Pendulum" and "Newton's Balls"
        http://www.officeplayground.com/newtonscradle3.html
        
In particular, the first link shows pictures of this device dating to around 1890. 
The "Invention and design" section says "in early 1967 ... coined the name 'Newton's Cradle'" but does not mention earlier dates.
I have not researched this myself, but I suspect that "Collision Ball Apparatus" was the earlier name used in physics demos, and that a search under that name might bring up better/alternative explanations of how this device actually works.
A variation of this physics demo consistes of balls on a track (straight or curved, grooved or parallel rods):
"version of Newton's Cradle"
    http://www.hope.edu/csi/Activity_Kits/Newtons_Balls_Background.pdf
    
"Rolling Collision Balls"
    https://www1.fishersci.com/wps/portal/PRODUCTDETAIL?productId=703758&catalogId=29101&pos=23&catCode=SE_SC&fromCat=yes&keepSessionSearchOutPut=true&brCategoryId=56821&hlpi=y&fromSearch=    
"COLLISION BALL APPARATUS"
    http://www.ginsbergscientific.com/0cat_details01.asp?cid=3676
    
I hope these observations are helpful.
Quisicaluser (talk) 16:22, 29 June 2009 (UTC)
thread_title:  Other Names; History; How it works; Variations 

message: Every German physics textbook of the 19th century shows a picture 
of such a device, it is most often called "Stossmaschine" (= impulse machine).
One of my books names it "Stossmaschine Mariotte", thus one should look 
for Mariotte as the inventor. Every German Grammar school had/has such a 
gadget to demonstrate conservation of impulse. 
I own a 1972 catalog from Griffin & George (English company making and 
trading laboratory and school equipment) but there is no such device 
at all! For strange reasons the Mariotte impact machine was not popular 
in English schools/universities, maybe the same is true for US?  
http://de.wikipedia.org/wiki/Kugelsto%C3%9Fpendel  names Mariotte
:A drawing of Newton's cradle (not named) appears on p. 223 of The Book of Popular Science, Vol. 5 (1958 ed.) by The Grolier Society. It's in an article entitled Experiments With Sound which also contains older devices such as the Siren which is mentioned by 19th century authors such as Rayleigh and Helmholtz. The article could explain the popularity of the cradle and it appearance as a novelty in Canada and the US in the sixties. --Jbergquist (talk) 22:21, 17 January 2012 (UTC)
thread_title:  German tradition 

message: I don't think the pop culture section contributes at all to this article. The pop culture references are far too obscure, especially when you consider that a newton's cradle is a common prop for an executive character's desk. It looks to me like some random users noticed a newton's cradle in their favorite pop media, looked it up on Wikipedia, and thought it would be cool to add cruft to the article. I was about to simply remove the entire section, but as I am Wikipedia (editing) noob I'm going to ask in advance. What do you guys think? AuntieNeo (talk) 04:40, 6 November 2009 (UTC)
thread_title:  Do we really need a pop culture section? 

message: Will the effect be observed in the case only deformations of metall are involved and the middle balls are well fixed?--MathFacts (talk) 10:38, 12 February 2010 (UTC)
thread_title:  What if the middle balls are not hang but fixed? 

message: Does anyone have proof that it has been called 'Newtons Balls,' as it does sound a bit, well, you know, DIRTY. He's just A Common Man! (talk) 07:53, 20 February 2010 (UTC)
replies: text: Oh, so it was not only me who bursted out laughing at that name. ROTFL. -andy 77.190.12.208 (talk) 17:33, 25 August 2011 (UTC)
thread_title:  Newtons Balls? 

message: Another thing I've noticed is that nowhere is there any reference to a text/source to support "the wave propagates through the balls at the speed of sound etc". I can categorically tell you that that is not the case. From some of my recent experimentation it is clear that the wave propagation time is on a scale of milliseconds not microseconds. Can anyone else shed any light on this??  —Preceding unsigned comment added by 136.206.1.20 (talk) 15:57, 3 March 2011 (UTC)
replies: text: The effect of pressure waves was the original wiki explanation, and their presence is interesting so I just included a detailed description of how they are involved. Ywaz (talk) 13:39, 15 January 2017 (UTC)
thread_title:  Explanation of the Physics? 

message: This article states: "The first time observer may find this visually intriguing and counter-intuitive. If a person charged into one end of a row of adjacent people then one would intuitively expect the whole row of people to be moved, rather than the last person in the row to acquire the kinetic energy." It is not well established that one person running into a row of people would cause them all to move or indeed any of them to move - there are just too many variables here for this analogy to be meaningful.  — Preceding unsigned comment added by 192.158.61.139 (talk) 13:44, 24 June 2011 (UTC)
replies: text: There's only one way to find out what would happen in such a scenario. 173.180.202.22 (talk) 07:40, 6 April 2012 (UTC)
thread_title:  What? 

message: After spending a lot of time working on the physics explanation, I wanted to justify what may seem like a lengthy section.  Other than finding out what it is, I think the main reason anyone would visit the article is to find out how it works.  There are a lot of inaccurate solutions on the internet, and the previous explanation in Wikipedia was wrong (based on bouncing shockwaves which the authors of the reference subsequently renounced because the time it took was much slower as predicted by Hertzian compression).  Rather than simply giving the 5 interdependent 2nd order differential equations and asking the reader to work out the details, or otherwise giving complex math, I gave a more wordy treatment in the expectation that the average reader would be at a high school physics level. Most presentations of the device and all of the iPad apps and Java programs I've seen use the simple solution, which is not completely accurate, given that it is supposed to be a physics demonstration.  Even the best apps are not doing a real cradle justice because they do not include the errors away from the ideal.  They have included friction and heat loss, but it is not enough to give the feel of a real device. 
Ywaz (talk) 16:04, 9 July 2011 (UTC)
thread_title:  Justification for detailed physics, and a spreadsheet 

message: This is totally misleading for unaware users! These are animated GIFs and would not respond to any mouse interaction whatsoever!! I make a bet many users already tried to take influence on the motions by using their mouse. But alas, this is not Flash, it's just a (beefed-up) image file. -andy 77.190.12.208 (talk) 17:38, 25 August 2011 (UTC)
replies: text: I fixed them.  Didn't know how to upload on top of the old ones on Commons, so if someone wants to fix that, please go ahead so the file history is preserved.  Lurlock (talk) 02:21, 6 October 2011 (UTC)
thread_title:  "Drag the balls to create different motions" 

message: Joe Smitherman?
Shouldn't the invention of this by Joe Smitherman in 1965 be mentioned? http://www.angelfire.com/home/sesquiq/joe.html -- 76.104.59.252 (talk) 16:54, 30 November 2011 (UTC)
thread_title: Who Invented It?

message: One of the other factors for losses must be the sound generated by each impact, not just heat from deformation and air resistance.  In fact I think the sound is probably the major source of energy loss in an otherwise balanced system, but I have no evidence of this.  Can somebody with the numbers add this ideas to the Losses section?   Nutster (talk) 23:52, 25 April 2012 (UTC)
replies: text: Also, if the balls are big enough that they deform on impact, some of the kinetic energy is lost to breaking metallic bonds and changing energy at the grain boundaries, not just to heat.--Wikimedes (talk) 19:00, 8 July 2012 (UTC)
thread_title:  Energy losses 

message: initial conditioning:
# one ball raised and released at once (from one side)
# one ball from each side raised and released at once synchronously
# two balls raised and released at once (from one side)
# two balls from each side raised and released at once synchronously
# three balls raised and released at once (from one side)
# four balls raised and released at once (from one side)
# all balls raised and released at once (from one side)
# separate the five balls in groups of 2 - 2 - 1 balls and synchronously release them
# all balls raised and released one by one at short intervals (by holding them carefully with one hand) (from one side)
# stabilize the central ball, release synchronously two surrounding balls - one from each side - and at the half of the extreme divergence position release the other two flank balls
# make the central ball to oscillate, then repeat the upper step, this looks like step 9 but less energetic
then:
# describe all the above mathematically
# replace one ball with one magnetic ball from one flank
# replace the two outer balls from both flanks with magnetic ones
# use magnets of various magnetic magnitudes
# describe all the above mathematically
# find new examples
— Preceding unsigned comment added by 2A02:587:4110:2B00:F0D5:204:77E2:3637 (talk) 09:53, 24 October 2016 (UTC)
thread_title:  more complex arrangements of the five balled cradle 

message: five  chrome steel ball bearings yields
:five  chrome steel ball bearings
which is not good grammar.  Either amend the 'convert' template, change the template being used, or don't use a template.
—DIV (120.18.150.196 (talk) 07:20, 20 November 2016 (UTC)
thread_title:  Crappy grammar from template 

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thread_title:  External links modified 

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thread_title:  External links modified 

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thread_title:  External links modified (February 2018) 

message: Hi, I noticed that the sentence reading "the time to complete a collision decreases in softer materials" seems to have it backward... isn't rubber a slower collision than steel?
Thanks. 208.76.28.70 (talk) 21:34, 22 February 2018 (UTC)
replies: text: I made the correction. Ywaz (talk) 20:51, 6 March 2018 (UTC)
thread_title:  Typo? Time to complete collision ____ (increases or decreases) in softer materials. 

message: In the section "Effects of Different Types of Balls", this sentence needs to be fixed. "If the solid balls are too large, is be lost as heat, because the elastic limit increases as radius 1.5 but the energy had to be absorbed and released increases as radius3"  — Preceding unsigned comment added by Jamezism (talk • contribs) 16:20, 15 December 2018 (UTC)
thread_title:  Sentence needs proof reading and correction.