Talk:Jerk (physics)

message: I would like to add something about 'metres per second per second', or 'm/s/s', but I am unable to think of a good location in the article to place this. I think this would be a useful addition for those like myself that only have an education in physics up to high-school level, where the full wording is more intuitive than m/s³. 94.173.75.170 (talk) 12:01, 21 October 2023 (UTC)
thread_title: Full wording for m/s³

message: http://www.wordorigins.org/wordorj.htm states:
Do you want to know who a jerk is?! My english teacher!!!!!! I mean seriously, he LOVES to pick on me and my friends. GRRRR!!!!!! I HATE HIM!!!!!
Jerk is an old word, dating to the sixteenth century. The word echoes the sound made by a short, sharp movement. The word is unremarkable, except that it has several modern, slang usages that are interesting.
A soda jerk is someone who makes a living by jerking, or pulling, sodas at a lunch counter, the name coming from the jerking motion required to open a tap.
To jerk off is to masturbate, again coming from the motion required for men to engage in this activity. Founded by a Mr. Jerk Gosling in 1623.
A jerkwater train was originally a small locomotive that serviced branch lines. Its small boiler requiring frequent filling by train crews which would have to dismount, form a bucket brigade, and jerk water from a river to feed the steam engine. The term dates to the 1870s and is American in origin. The term jerkwater town eventually came to mean any rustic or backwards town, along a train line or not.
Finally, the most common usage of jerk, meaning a fool or inept person, probably derives from jerkwater. A jerk being a resident of a jerkwater town. This usage dates to the 1930s.
The term jerky, meaning dried and preserved meat has a different origin. That is a corruption of the Peruvian Spanish charque, meaning (what else?) dried and preserved meat.
I didn't have time to modify the article. I would like to point out that while "jerk" often implies stupidity or incompetence, that is usually not the most common usage. The most common one, as I've heard, refers to someone who frequently behaves in a manner inconsiderate of other people (on a local scale, as in "That jerk cut me off," or on a global scale, as in "Chicks dig jerks"). 
23:22pm EST 2004 March 21
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Would you please add references that give more information about the Jerk.
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I added the English-language slang meaning of Jerk. If this qualifies as a dicdef and therefore does not belong, remove it.
:It does and I did.—Herbee 06:40, 2004 Mar 17 (UTC)
I believe I'm correct in saying that the origin of the term is unclear but may have come from one of those two derivations. If I am not, and there is someone who knows its correct origin, please post it. Mike Church 10:02, 14 Mar 2004 (UTC)
thread_title: Definition

message: There are some terms for the fourth derivative here, but the article is missing the only one that I've heard before, "twitch". Has anyone else ever heard this term in reference to the fourth derivative of displacement? --Monguin61 05:46, 20 December 2005 (UTC)
replies: text: I've heard of "twitch" before, and I think it was in the context of the 5th derivative, and I swear I read this somewhere on Wikipedia. Also, it spoke of the unofficial name of another derivative (6th?), being "impulse". I can't find this anymore either.  — Preceding unsigned comment added by Zom-B (talk • contribs) 21:51, 17 December 2022 (UTC)
thread_title:  Fourth derivative 

message: Isn't it impossible to accelerate instantaneously? Motion is an infinitely differentiable entity; there is no such thing as an infinite jerk, just a very very high jerk.
: Yes, that's true. Infinite jerk over an instant of time is an idealization, just like infinite force over an instant of time is sometimes used to characterize an elastic collision between two objects. PAR 19:24, 12 January 2006 (UTC)
replies: text: The right answer is double: 1) physically it is possible to accelerate instantaneously, given that the definition of "instantaneously" means in fact "faster than the precision of the measure" 2) mathematically infinity is avoided by using a Dirac distribution ; in that case you must use distributions (in the sense of Laurent Schwartz) instead of functions and then you avoid the "infinite jerk" nonsense  —Preceding unsigned comment added by 217.154.243.205 (talk) 14:59, 12 August 2010 (UTC)
thread_title:  Infinite jerk 

message: "with some nonzero positive value for tongue-in-cheek" - very clever, I rate that! --LeakeyJee 07:28, 4 May 2006 (UTC)
thread_title:  tongue in cheek 

message: Where did all this relativistic, mass-changing-with-velocity, yank stuff come from? 16:31, 22 September 2006 (UTC)
replies: text: I am pointing out that there is no source for the information. I am familiar with special relativity. Why should I believe that special relativity is at all relevant to the applications of jerk? Melchoir 19:44, 22 September 2006 (UTC)
thread_title:  Original research 

message: has a preference for linearity--great. But how about more debate/exploration on Nature's "preference", if the preference exists, for second order differential equations? One way to explore it would be to check if there is something mathematically significant that happens or doesn't happen with linear third order partial differential equations. Does all hell break loose in the solutions or what? This is like asking why we have 3 space dimensions instead of 38 or 190 spatial dimensions.Rich 00:02, 22 April 2007 (UTC)
replies: text: Nature has no special preference for the 2nd derivative of position, or of any other. However, the Taylor series (or Maclaurin series) approximation shows that for most of the kinds of functions that describe motion, lower derivatives provide a good approximation to the value of the function. Thus, with important exceptions, you can approximate real-world motion by using lower derivatives. In fact, when you do this, you choose the highest order derivative to use such that the next higher-order derivative term is negligible in value over the domain of interest. This is why considering additional orders of motion derivatives (such as jerk) becomes, in general, an exponentially less interesting to do. David Spector (talk) 14:39, 28 December 2011 (UTC)
thread_title: Now jerk is 3rd deriv., which reminds me...people debate/discuss about whether Nature

message: There's no way the majority of English speakers first think of the third derivative of displacement when defining the word Jerk.  Thoughts?--Loodog (talk) 16:42, 9 December 2008 (UTC)
replies: text: Agreed, most people are probably thinking of the wiktionary definition anyway (of a person). Joshdboz (talk) 20:13, 13 December 2008 (UTC)
thread_title:  Article move: Jerk->Jerk (physics) and Jerk (disambiguation) ->Jerk 

message: This article has very little information beside the physical description and formulae concerning the jerk. It should be supplanted by information from G-force#Rate_of_change_of_acceleration. --Pero-- 78.0.226.174 (talk) 09:38, 28 April 2009 (UTC)
thread_title:  Very little information 

message: Most readers will not understand the differential equations, and it is difficult to see where the "jerk" comes into the graph provided if you do not already understand the concept.  It would be useful to have a graph that shows position, velocity, acceleration, and jerk, separately for the same example. -- Beland (talk) 22:43, 30 August 2009 (UTC)
thread_title:  Further illustration needed 

message: This section is COMPLETELY WRONG. It needs cleaning. Currently it describes a second-order motion profile with limited positions, velocity and accelerations, but unlimited jerk. Here jerks are "infinite" (a Dirac would be a more precise term) 8 times (at each bounadry of each segment)  —Preceding unsigned comment added by 217.154.243.205 (talk) 14:52, 12 August 2010 (UTC)
thread_title:  Third-order motion profile 

message: This sentence before the diagram:
In this way, jerk can seem counter-intuitive, because it is not something people experience qualitatively on a daily basis.
was replaced by this:
A familiar example of jerk is the rate of application of brakes in an automobile.
The two examples after the diagram did not appear to be related to jerk, and were replaced by an expansion of the example about applying brakes. Neither of the two previous examples is appropriate to this discussion. The paper-tearing is due to a large acceleration, not jerk. When the force is applied gradually, the amount of force is equal to the muscular strength alone.  When the paper is held loose and then jerked tight, the momentum in the hands and arms is added to the muscular strength.  The paper attempts a large deceleration of the hands, and the added force is equal to m*a, not m*da/dt.  In the case of silly putty, the issue is strictly related to the velocity (as was correctly stated in the text of the example, “the speed with which you pull”), and has nothing to do with da/dt.
RobH103 (talk) 02:11, 24 December 2012 (UTC)
replies: text: I removed this section, including the template requesting additional citations and reliable sources as announced. Purgy (talk) 10:50, 21 September 2014 (UTC)
thread_title: Non-calculus explanation

message: I have added two new section to this page and revised some finessses. I plan to review the whole article, put together the available information and try to streamline some broad unit considerations, thereby also getting rid of the officially deprecated gal. Purgy (talk) 11:13, 7 August 2014 (UTC)
thread_title:  New Sections and General Revision 

message: I suggest placing the mentioned section of this here articel in the page about Chaos theory, because the importance of the associated 3. order non-linear DEQs belongs largly to the possible chaotic behaviour of their solution and the realisation of these systems in appropriate circuits is also of rather mathematical interest, imho. The conection to jerk in Mechanics is rather restricted to the degree of the DEQs. Thoughts, anybody? Unwithspoken, I'll implement this in roughly 3 weeks. Purgy (talk) 09:19, 22 August 2014 (UTC)
replies: text: I did as announced. Purgy (talk) 10:36, 21 September 2014 (UTC)
thread_title:  Split section ''Jerk Systems'' to [[Chaos theory]]? 

message: After having been hinted to do so, I removed the rating of "Start class" on the quality scale, in the hope to get some advice from the Physics portal how to improve this article further. Purgy (talk) 11:44, 22 August 2014 (UTC)
replies: text: Portals don't normally assess articles for quality - that's a WikiProject function, in this case Wikipedia:WikiProject Physics. Somebody there should soon notice that this page is now in  (there are presently 25 pages in that cat, a low number compared to, say, ); if you need a particularly fast response you could drop a note at Wikipedia talk:WikiProject Physics/Quality Control. --Redrose64 (talk) 12:44, 22 August 2014 (UTC)
replies: text: I must confess, that I overlooked that difference between "portal" and "project". This is in no way to express any lower appreciation of both, but only due to my newbie- and sloppiness; and who am I, to need a particular fast response? Lucky, to get sooo much. :) Purgy (talk) 15:12, 22 August 2014 (UTC)
thread_title:  Initiating reassessment 

message: All but one of the references on this page gives 404 not found  — Preceding unsigned comment added by 5.151.0.2 (talk) 21:19, 2 October 2016 (UTC)
replies: text: As of just now, all given links lead to appropriate targets. Maybe there is something wrong with your network permissions? Purgy (talk) 05:59, 3 October 2016 (UTC)
thread_title:  All but one reference is dead (404) 

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thread_title:  External links modified 

message: "... The beginning of an emergency braking lets the body whip forward faster than the achieved acceleration value alone would accomplish, ..."
.
As stated, this is wrong in more than one way.  
.  
To begin, remember the body does not 'whip forward', it merely continues to travel at the same speed it has been travelling.  This might seem like I am picking nits, but the frame of reference is important.  Sure you could choose a noninertial frame of reference like the car that has begun to brake, but that just makes things more complicated....so complicated that errors like those made in this statement could be easily overlooked.
.
Once we are back considering things from an inertial frame of reference, it becomes plainly obvious that the body cannot "...whip forward faster than achieved acceleration value alone would accomplish...", because the body just continues to move forward until acted on by seat belt of otherwise.  
If anything, looking at the peak acceleration of the car would overestimate the relative velocity of the body with respect to the car.
.
So to review the ways in which this statement is wrong:
1. The chosen frame of reference weird and overly complicates things.
2. Jerk does not somehow disengage the relationship acceleration and velocity.
3. The direction of the effect, claimed as evidence, is exactly the opposite in reality as that suggested by the claim.
.
.
BGriffin (talk) 19:05, 15 June 2017 (UTC)
replies: text: Please, have in mind that the effects of jerk are not described by Newton's laws of motion, which of course hold in these circumstances, but are of physiological nature, without violating physics. Living human bodies are neither rigid nor liquid bodies, with forces only acting on them, but exact themselves forces. I have tried to address your legitimate concerns in the paragraph. Purgy (talk) 10:41, 16 June 2017 (UTC)
thread_title:  Incorrect, compoundly. 

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message: I don't understand this sentence- no generally used term to describe its scalar magnitude. The next sentence says the units of jerk are m/s3, which is scalar. So it seems that it is just like acceleration which can have both a scalar acceleration value or vector. Volunteer1234 (talk) 13:11, 22 August 2018 (UTC)
replies: text: In nitpicking manner one should perhaps say that the unit for Cartesian jerk-components and for the scalar magnitude of the jerk-vector is such and such. In any case I am not aware of a "generally used term" for this magnitude, and also not of any units, directly applicable to vectors. The setting is similar to acceleration, that intrinsically has a vector quality, and, like all vectors, any acceleration vector has a magnitude, which has appropriate dimension and units. I changed accordingly. Purgy (talk) 16:43, 22 August 2018 (UTC)
replies: text: Still seems wrong to me. There is a generally used term for jerk's scalar magnitude, and it is jerk, the same as there is a generally used term for scalar acceleration- acceleration. Volunteer1234 (talk) 17:05, 22 August 2018 (UTC)
replies: text: Did the last edit address your concerns? I'd like to remark that I avoid notions like "scalar acceleration", because acceleration is intrinsically a vector, the "norm" of which is, also intrinsically, a scalar, which may carry units. It is not the case that arbitrary components of a vector employ the same units (e.g. polar coordinates). I agree that jerk/acceleration are both used to denote the corresponding vectors and their norms - in rigorous contexts such is generally called "abuse of notation". Purgy (talk) 07:07, 23 August 2018 (UTC)
replies: text:  It is getting better. It now just seems too long and not a very interesting fact for this to be in the small lead. I moved it to the 3rd sentence Volunteer1234 (talk) 17:03, 23 August 2018 (UTC)
replies: text: It might well be a matter of taste how interesting it is to make explicit wide-spread abuse of notation, but I won't interfere, if you like it this way. :) Purgy (talk) 07:30, 24 August 2018 (UTC)
thread_title:  "no generally used term to describe its scalar magnitude" 

message: I note that the first three terms in the list below are all from Latin, whereas the fourth is not.
position
velocity
acceleration
jerk
What term from Latin could be used to replace "jerk"?  — Preceding unsigned comment added by John Link (talk • contribs) 21:25, 25 September 2018 (UTC)
replies: text: I side your view these being linguistically inconsistent terms within this connection, but to my knowledge there is no serious contender with an even near frequency of use, and I know of none with Latin or Greek roots. Till someone finds a suitable term with sufficiently documented and frequent use, WP seems bound to stick with alone the inconsistent jerk. Purgy (talk) 07:19, 26 September 2018 (UTC)
thread_title:  Linguistic inconsistency 

message: Section Physiological effects and human perception: The feeling of being pressed into the seats in a high-powered sports car is the force of acceleration. Jerk only occurs initially when the engine torque increases from zero, causing a remarkable increase in acceleration (jerk).
I don't think that's correct. As a vehicle's velocity increases, so does air resistance, decreasing the acceleration until it reaches 0 at the vehicle's maximum velocity. Does this not mean that there is a jerk throughout the period of acceleration? The jerk would be a large and positive at the initial acceleration, then small and negative until acceleration returns to 0 at maximum velocity.
I've amended the explanation to avoid having to remove it. However, it seems to me that the relevance to physiological effects is more in the acceleration than the jerk, and the example may not be appropriate in that section. Thtatithticth (talk) 04:03, 5 March 2020 (UTC)
thread_title:  Incorrect explanation? 

message: This deletion debate may be of interest to those watching this page. XOR'easter (talk) 19:22, 14 March 2020 (UTC)
thread_title:  [[Wikipedia:Articles for deletion/Crackle (physics) (4th nomination)]] 

message: I'm guessing "cam profile" may refer to Computer-Assisted Manufacturing, related to CAD (computer-aided design), which is one of a few contexts where I have encountered the concept of jerk (mechanics).
The word CAM should be uppercase, and maybe it should be a bluelink (wiki link) the first time it appears. Unless it is referring to cams, the wheels that are not round, or something else. Cams do have a profile or shape, it determines how they move the thing they push as they rotate.
This article doesn't prominently mention feedback systems of any kind, and actually enforcing a jerk limit requires feedback from the moving part. This is especially true in the elevator example, where the mass of the moving elevator car is variable depending on the passengers. But it is variable even within a robot, as the motor gets weaker or the friction increases, and a fixed program that worked during R&D starts to fail in the field with older devices. Those are some nightmares I hadn't thought about in five years. Ahh, engineering. 209.94.144.13 (talk) 21:16, 24 December 2020 (UTC)
thread_title:  Should it say "CAM profile" every time it says "cam profile"? 

message: When was the first time it was called "jerk" and why? George Rodney Maruri Game (talk) 00:06, 30 March 2023 (UTC)
thread_title:  History?