Talk:Simple machine

message: Give me strength.  — Preceding unsigned comment added by 79.79.153.6 (talk) 14:16, 24 July 2022 (UTC)
thread_title: A screw IS an inclined plane

message: Could we consider adding the Gear as an item under the variations list?  I have found several sources (including wikipeida's own article on gear) that define it aas a simple machine.--Cpkondas (talk) 19:44, 29 January 2008 (UTC)
replies: text: Wikipedia's article is, ironically, not a reliable source for the verification of other Wikipedia content.  You could add it to the variations list if you have other reliable sources.  I only found a single reference (in the list above that mentioned the gear as a simple machine.  That one reference didn't seem strong enough to me.  Rossami (talk) 23:59, 30 January 2008 (UTC)
replies: text: Here is one external source: http://www.mos.org/sln/Leonardo/InventorsToolbox.html  Do you need a definite number to add to the variations list?  --Cpkondas (talk) 18:07, 31 January 2008 (UTC)
replies: text:  There's no magic number.  It's a qualitative assessment made by the consensus of editors who choose to discuss it here.  Your source is the same Boston Museum of Science reference we found above.  It doesn't really call a gear a simple machine.  It lists gears in the section titled "Other Elements of Machines", a heading at the same level as the section titled "Simple Machines".  (I must also admit that my confidence in that reference is reduced by their unexplained omission of the inclined plane from the list of simple machines.)  Rossami (talk) 23:20, 31 January 2008 (UTC)
replies: text:  I agree.  A gear is a special application of a simple machine such as a wheel. In fact, it's simply a wheel that needs a lot of "friction", the way a tire on your car needs some friction against the road. Look at a Gear#Rack_and_pinion, which is clearly a gear. Now squint and pretend the pinion is smooth instead of toothed, like the rubber roller that feeds paper through a printer. Pretend the rack is also smooth (like the paper).  Is there any difference in the mechanical action of a rack-and-pinion vs a rubber roller and paper?  Each is converting rotational force into lateral force. Depending on the magnitude of the torque and the material you need to move, you simply vary the surface of the pinion, perhaps smooth like rubber, or as rough as sandpaper, or even so rough that it's toothed to match a toothed rack.  A worm gear is a special application of the inclined plane.  Seems like it's a helically shaped inclined plane that transfers rotational movement to longitudinal (not lateral) movement. Petershank (talk) 23:45, 4 January 2011 (UTC)
thread_title:  Adding to the variations list

message: I think that any machine that is simple could be called a "simple machine" but that only the 6 (or 4,5,7 ect) "simple machines" discussed on this page falls under the category of "Simple Machine" (notice caps). This way we indicate that we a talking about the result of classical mechanical reductionism and not just of any machine that is simple. Jesper Jurcenoks (talk) 23:42, 1 April 2008 (UTC)
thread_title:  Simple Machine or simple machine 

message: On 25 April 2008, Beland added the  tag at the top of this Talk page.  First, I despise those templates.  They permanently "tag" a talk page and confuse future editors long after the problem has been addressed.  Second, I'm not sure that diagrams are appropriate on this page.  This article discusses the aggregate concept of a "simple machine" and prominently links each of the simple machines.  Those drill-down pages are very well diagramed.  I don't know what picture you could put here that would benefit readers without merely cloning in content that's already better discussed elsewhere.  Rossami (talk) 16:15, 27 April 2008 (UTC)
replies: text: I agree with Rossami, no need for pictures here Jesper Jurcenoks (talk) 13:11, 11 May 2008 (UTC)
replies: text: I generally agreed that there should be no pictures, but then I found a chart of simple machines from a 16th century encyclopedia.  It seemed to illustrate the topic so well that I put it in the article.  Hope nobody minds too much.  --ChetvornoTALK 12:17, 26 June 2008 (UTC)
thread_title: Request for images 

message: what's the etiquette? certain things on here are unlikely to rear their ugly heads again eg the mnemonic. Human fulcrum needs to go. Rolamite disussions should all go. I will start to delete, you can always put it back if you feel it adds anything. I'd also like to edit my 'wheel is not a machine' section back to the basic argument and remove most of the debate with Rossami.
PS. Glad to see the article in much better shape than last time I visited.  —Preceding unsigned comment added by Jimbowley (talk • contribs) 22:07, 2 January 2009 (UTC)
thread_title:  editing talk pages 

message: This article says that there are six simple machines, but there really are only three. A pulley is just a wheel with a rope through it, a wedge is just two inclined planes placed back-to-back, and a screw is just an inclined plane wrapped around a nail.  —Preceding unsigned comment added by 71.167.228.99 (talk) 02:30, 4 March 2009 (UTC)
thread_title:  How many simple machines? 

message: The blade focuses energy on a smaller point, thus manipulating and allowing it to conform to the definition of simple machine.  Some would argue that the blade is a variant on the wedge.  This is not true as one could remove the point of the wedge and have it remain just as potent as before while removing the edge of a blade would dramatically reduce it's ability to convert energy.  The edge is inherent to the blade, not to the wedge. Demagoguery (talk) 23:02, 25 March 2009 (UTC)
replies: text: Some would argue... - who? WP:RS please. Vsmith (talk) 02:39, 26 March 2009 (UTC)
replies: text: This debate is interesting, but the topic is already being discussed under the heading  'About the Wedge' above.  Maybe we should move these entries up to that heading.  --ChetvornoTALK 05:09, 26 March 2009 (UTC)
replies: text: 24.90.235.104 "argues" it above under "About the Wedge". Rico402 (talk) 09:43, 27 March 2009 (UTC)
thread_title:  The Blade as a simple machine 

message: Basic enough? I think that is not an 'enough' rigorous point. The real question In My Humble Opinion should be, "can it be represented by other simple machines"? That is, if it (hydraulics) transforms one mechanical energy mode into another and no (other) simple machine can replace it, add it to the list. Perhaps it wasn't known at the time of the original list. Though if one includes machines made in the digital age, like the transistor, the list may grow unwieldy. But then you've nearly reduced it to two machines!24.146.226.25 (talk) 21:46, 29 June 2011 (UTC)
thread_title:  Hydraulics 

message: Well, our colleague Chetvorno in a desire to keep the unusual definition that "simple machine is a device that transforms the direction or magnitude of a force," has reverted all of my edits with little attention to their individual value.  I have to say that his statement that a " 'simple machine' has a specific meaning, which is the traditional concept of a force scaler or amplifier linkage" captures the essence of mechanical advantage, but does not represent a transformation of the direction and magnitude of a force.  All things change the direction and magnitude of a force in some way.  I am willing to let him have his way with this topic, I have had this experience before.   However, I do have one regret, that the listing of simple machines stops with those identified in the Renaissance and does not include those recited in the later years of the Industrial Revolution, for example the listing of 60 or more simple machines shown in the figure attached to this article or the more than 800 simple machines identified by Franz Reuleaux.  Prof McCarthy (talk) 22:34, 29 November 2011 (UTC)
thread_title:  800 Simple Machines 

message: The list of simple machines discussed in this article is known to have been identified by the time of the Renaissance.  During the Industrial Revolution that followed many additional simple machines were identified.  I assume gears may be considered examples of the wheel and axle, however their engagement to provide power transmission is not among the simple machines of the Renaissance.  More importantly, the discovery of the involute tooth which makes standardization and commercialization practical is of fundamental importance.   I would propose that cam mechanisms, the geneva wheel, escapements, the universal joint, and the flyball governor are all examples of simple machines that were discovered after the Renaissance and deserve consideration as fundamental components used to make more complex machines.  Some would consider Watt's linkage to be of such importance that it qualifies it as having the significance of a wheel and axle, because it is considered to have made the steam engine practical.  Why is it off-limits in this article to simply mention that after the Renaissance other simple machines were identified? Prof McCarthy (talk) 06:22, 1 December 2011 (UTC)
thread_title:  Did identification of simple machines end in the Renaissance? 

message: I am trying to get Chevorno to address whether it is enough to leave the sentence "a simple machine transforms the magnitude and direction of a force" in the lead.  This would allow my to reinstate the other 24 or so edits.  His mass elimination of these edits seemed an ill-considered action to maintain this one sentence, which I had simply moved to a later section.  I have asked on his talk page if I may interpret his silence as approval. Prof McCarthy (talk) 01:37, 2 December 2011 (UTC)
thread_title:  No word from Chetvorno as yet. 

message: I have not heard from anyone, so I assume that if I leave the sentence "a simple machine transforms the magnitude or direction of a force" alone, though most everything does this, and work on the remaining parts of this article, I will not have my edits completely reverted.  At least I hope this is the case. Prof McCarthy (talk) 18:20, 3 December 2011 (UTC)
thread_title:  I will try again 

message: This article describes a compound machine as a series of simple machines and computes the mechanical advantage of a compound machine as the product of the mechanical advantage of simple machines.  This was obtained from the reference:  
It is important to recognize that this is a special case that is useful for introducing elementary school students to the idea of mechanical advantage, and not a description of machines in general. Prof McCarthy (talk) 19:22, 3 December 2011 (UTC)
thread_title:  Compound machines 

message: The section Simple machine#Alternate definitions exposes the error in a focus on "the transformation of the magnitude or direction of a force."  This is a useful simplification if the only concern is the six classical simple machines.  But there are many other machine components that transform the magnitude and direction of forces.  In fact a close look at most devices shows that they transform forces in some way---please see my examples of pillars and a dam above.  The critical concept in understanding classical simple machines that has an important modern form is mechanical advantage.  From this point of view, hydraulic systems are clearly simple machines, though not one of the classical cases.  The expansion of the list of simple machines in the late 1800's is what lead to a revision of the basic view of the analysis of machines that has now been in place for over one hundred years. Prof McCarthy (talk) 19:36, 3 December 2011 (UTC)
thread_title:  Alternate definitions 

message: I renamed the section "Frictionless analysis" to be "Mechanical advantage," because this is what is discussed in this section.  The derivation of mechanical advantage based on work is the standard approach used in the various notes for elementary schools.  However, this is better done using power, because mechanical advantage depends on the configuration of the machine, and is actually an instantaneous property like velocity.  In contrast, work is path dependent and is best used for simple cases, such as falling weights, unless the displacement is held to be very small, in which case it becomes a velocity analysis. Prof McCarthy (talk) 16:24, 6 December 2011 (UTC)
thread_title:  Frictionless analysis 

message: The section on "Self-locking machines" is based on the reference Gujral, I.S. (2005). Engineering Mechanics. Firewall Media. pp. 382. ISBN 8170086361.   It seems to say that if the efficiency is poor enough, the machine will be self-locking.  I guess this is a way of saying there is good in a poorly performing machine. Prof McCarthy (talk) 05:07, 7 December 2011 (UTC)
replies: text: The analysis of self-locking due to friction does not seem to be appropriate for this article on simple machines for a number of reasons.  Perhaps the most important is that it is overly simplified to the point of being incorrect in the cases where it matters the most, the inclined plane.  Self-locking due to friction is a characteristic of the analysis of an inclined plane and includes the wedge and power screw.  The mechanical advantage of a frictionless inclined plane is 1/tanφ where φ is the angle of the inclined plane.  In the presence of friction, let the angle of the plane where friction forces balance be α, then the mechanical advantage is 1/tan(α+φ), when raising a load.  The system is self-locking if α≥φ.  Clearly the inclined plane with friction has the efficiency η=tanφ/tan(α+φ).  If the friction angle is exactly α≡φ, and φ<10degrees, then  η≈φ/2φ = 1/2.  This analysis changes in the case of lowering the load.  This is a much more subtle analysis than simply adding work due to the load and work due to friction, and probably should be reserved for the articles on inclined planes. Prof McCarthy (talk) 18:00, 7 December 2011 (UTC)

text: Pete318, you are correct fasteners use internal forces and even mechanical advantage to maintain a structure.  Other examples are toggle clamps and door stops.  I believe you are right because the Renaissance notion of a simple machine is a device that moves loads, not one that makes a structure rigid.  Thank you.  Prof McCarthy (talk) 00:48, 25 January 2012 (UTC)
thread_title:  Friction and self-locking 

message: Apparently, there is not enough about the Pyramids and the Great Wall in other articles in Wikipedia, they must be discussed in this article as well.  It is true that Usher attributes a misreading of a Greek text on moving heavy loads as the source of the concept of Simple machines.  However, is it necessary to list all ancient monuments that have benefited from this construction technology?  I suppose we could include Stonehenge, the Mayan Temples, as well as the temples of the Acropolis.  Then there are mythical structures like the Tower of Babel, the Colossus of Rhodes and maybe the lost city of Atlantis. Prof McCarthy (talk) 07:37, 17 February 2012 (UTC)
replies: text: I really also wasn't done with the section. I just decided to add the section because it really is important to the history of the simple machine. Algamicagrat (talk) 15:02, 17 February 2012 (UTC)
replies: text: The Great Wall of China is the longest man made structure ever built in the history of mankind, with its present length of 8,851.8 km or 5,500.3 miles stretching into several provinces of China such as Liaoning, Hebei, Tianjin, Beijing, Shanxi, Inner Mongolia, Shaanxi, Gansu, and Qinghai. However, the Great Wall of China is a noncontinuous series of walls in different places, especially during the period of its initial construction. It was primarily built by several states during the Warring State Period in China to prevent attacks from other neighboring states. Later on, when the states vanished, leaving the Qin State in a unified China, Emperor Qin Shi Huang ordered the connection of the series of walls and termed it as “10,000 li Long Wall.” It was connected to prevent further attacks, that time from the northern nomadic tribes. Later on, the last reconstruction of the Great Wall undertook during the Ming Dynasty after change of several dynasties. The Ming Dynasty purposely reconstructed the wall to strengthen its defense further from the Mongol in the northern part of the country.
Prof McCarthy (talk) 15:39, 17 February 2012 (UTC)
replies: text: Good Point...Algamicagrat (talk) 23:55, 17 February 2012 (UTC)
thread_title:  Egyptians and the Great Wall 

message: Recent edits by our colleague 3/4-10 appear to assert an equivalence between machine elements and simple machines.  At least this is the way I interpret the following taken from the lede to this article:
:Various authors have compiled lists of simple machines and machine elements, sometimes lumping them together under a single term such as "simple machines", "basic machines", "compound machines", or "machine elements"; the use of the term "simple machines" in this broader sense is a departure from the neoclassical sense of the six essential simple machines, which is why many authors prefer to avoid its use, preferring the other terms (such as "machine element")
I believe is it appropriate to consider the phrase simple machine as referring either to a machine that is simple or to one of the set of six simple machines identified by Renaissance scientists.  However, machine element is a modern concept that should be separated from what is actually an odd concept that machines are constructed from combinations of six devices identified by Renaissance scientists.  As Usher notes this was a misunderstanding of a text on devices used to move heavy loads.  It was not the result of a scientific study of the decomposition of mechanical movement.  In contrast, Reuleaux did perform such a study of mechanical movement and constructed models of 800 different devices that can be considered machines that are simple.  As a result, Reuleaux identified the rotary, linear and direct contact joints, which he described a lower pairs and higher pairs, as the elemental components of mechanical movement.  These are the predecessors to what are now known as machine elements, and the list has expanded to other important mechanical components.  However, blending the terms simple machines and machine elements is to blur the important distinction between a failed tradition and its modern successful approach. Prof McCarthy (talk) 06:58, 13 March 2012 (UTC)
replies: text: The concept I was trying to cover is that one word sense of the term "simple machines" is only the 6 fundamental classical/neoclassical ones, whereas another word sense of the term treats it more like "machine elements" (for example, at least 2 of the cited refs use it in that sense). I personally would rather see people confine the term to the first sense mentioned, because it better allows for precise-while-brief (that is, succinct) communication. What I saw in the earlier version was the remnants of various editors coming here and disputing the definition of the term—the answer to that is to have the article explain that both word senses exist, even if one is not preferred. If anyone wants to work on refining the coverage so it's clearer, that's fine. — ¾-10 00:58, 15 March 2012 (UTC)
replies: text: I appreciate your thoughts on this.  I have had many run-ins with editors who insist this article must limit the notion of simple machines to the Renaissance view because of the many elementary school web-sites that use this as an introduction to technology.  I believe it makes sense to broaden the term to at least include the many simple machines that are represented by Reuleaux's models as well as other listings such as the figure in the lede.  While I do think there is a technical concern with blending this definition with machine elements, I could be persuaded that if elementary school teachers viewed axles, bearings, screws, gears and other machine elements as simple machines this could actually be a good thing for elementary school engineering, in particular, and machine theory in general.Prof McCarthy (talk) 01:18, 15 March 2012 (UTC)
replies: text:  I agree with the Prof that this article should discuss the Renaissance list as a historical item (which has been the previous consensus) and also that adding eg Reuleaux's work is appropriate. I also agree that we don't want to mix machine elements with simple machines Jimbowley (talk) 16:37, 10 July 2012 (UTC)
thread_title:  Machine elements v. Simple machines 

message: I think to improve this page we should include a comparision between simple machines and compound machines. I do not know how to explain it right so if you know how could you please edit it because I would just like to help this wikipedia page better. Thanks for your time.
~Lily Clarissa Smithers~  — Preceding unsigned comment added by 184.56.82.19 (talk) 17:54, 25 March 2012 (UTC)
replies: text: The article contains a section on compound machines that explains that a compound machine is made up of several simple machines connected in series.  What would you like to see added? --ChetvornoTALK 01:31, 26 March 2012 (UTC)

text: Very good food for thought. I for one would like to see this article contain a section called "alternative classification schemes" (or something along those lines) that basically says what Prof McCarthy said above. — ¾-10 00:38, 27 March 2012 (UTC)

text: The section as written is not incorrect. If you define a compound machine as a series of simple machines, then the equations etc are correct. The section does not state that all complex machines are compound machines. I have not come to an opinion on whether the section is useful for the article yet. Jimbowley (talk) 17:03, 10 July 2012 (UTC)
replies: text: I'd like to see a clearer separation between the classical Renaissance theory of simple machines and the different modern concept based on kinematic chains added by Prof McCarthy.  In the classical theory, still taught in physics classes, there are only 6 simple machines and "compound machines" consist of series of simple machines.  In the modern theory by Franz Reuleaux and others, there are hundreds of "simple machines".  Both theories are important, but in its present condition the article doesn't cleanly distinguish between them.  This will confuse nontechnical readers.  I think the two theories should have separate sections.  Perhaps the main body of the article can be devoted to the classical theory, which is what most readers want when they look up "simple machine", and a separate section at the end can explain "kinematic chains". --ChetvornoTALK 19:54, 10 July 2012 (UTC)
replies: text: Chetvorno, this is the spirit in which the section on kinematic chains was added.  Prof McCarthy (talk) 02:21, 11 July 2012 (UTC)
replies: text: It looks good as far as it goes, but the last paragraph of the introduction doesn't emphasize enough that it refers to a modern departure from the classical concepts.   Also, it needs to be clearer that the last two sections, "Kinematic chains" and "Classification of machines" are separate from the preceding sections which refer to classical machines.   Couldn't they be grouped under a section titled "Modern machine theory" or something like that? --ChetvornoTALK 21:00, 11 July 2012 (UTC)

text: My initial reaction is that this gives the modern theory more prominence than perhaps is necessary in this article on simple machines, but it may be a good idea. Prof McCarthy (talk) 22:15, 11 July 2012 (UTC)
thread_title:  Improvements  

message: I've only just noticed that the '2 classes' paragraph is wrong. 
A pulley is not characterized by the equilibrium of torques and movement around a pivot. Pulleys are about vector resolution of forces, there are no torques involved. And the movement is linear not around a pivot.
The screw is not characterized by the vector resolution of forces and movement along a line. The input is a torque. 
This all goes back to 2008 when there was a lot of discussion about what this page was about. I seem to remember that the agreement was that the 'list of 6' was at least a recognised historic list. Somehow the unreferenced '2 classes' seems to have slipped through and gone unchallenged since (unless I missed the challenge, if so, sorry). 
Jimbowley (talk) 12:08, 4 May 2012 (UTC)
thread_title:  2 Classes ????  

message: I don't know what it is about this page that so consistently attracts vandalism from anonymous users.  Looking at several years of history, the vandalism is not correlated with the school year (which had been my hypothesis in early lock-downs).  I fear that there is no choice but to restrict the editing of this article to confirmed users only.   Rossami (talk) 18:27, 28 May 2015 (UTC)
thread_title:  Protection 

message: THIS WEBSITE IS TRASH DONT TRUST IT  — Preceding unsigned comment added by 64.56.10.139 (talk) 14:45, 7 February 2017 (UTC)
thread_title:  Semi-protected edit request on 7 February 2017 

message: A spring is not a simple machine because it does not make work easier.If it simplified work then it would be considered a simple machine. a simple machine can be associated with springs like a rube goldberg machine.
                                                                                                                                      -Anna  — Preceding unsigned comment added by 2604:6000:B7CE:1800:649E:C921:91BF:8E9F (talk) 00:56, 4 April 2017 (UTC)
replies: text: Right.  A spring stores energy (work).  A simple machine doesn't store energy, it just transforms it, increasing the force while decreasing the velocity or distance moved (or sometimes vice versa).  In a frictionless simple machine the same amount of energy or power comes out of it moving the load as goes into it from the applied force.  In a spring, applying a force to it, flexing the spring, stores work or energy in it, which stays there until the spring is released. --ChetvornoTALK 01:18, 4 April 2017 (UTC)
thread_title:  Springs 

message: Re your recent edits to the "Ideal simple machine" section.  I don't see that the equality of velocity ratio and distance ratio is limited to certain machines, it seems to me it is a property of all 6 of the classical simple machines (this section is about the 6 Renaissance simple machines; not cam followers)  
For any simple machine, let \mathbf{x}_\text{in}(t) = [x_\text{in}(t),y_\text{in}(t),z_\text{in}(t)] be the point at which input force is applied to the machine, and \mathbf{x}_\text{out}(t) = [x_\text{out}(t),y_\text{out}(t),z_\text{out}(t)] be the point at which the machine applies force to the load at time t.  \|\cdot\| is the Euclidean norm.  From the Ideal simple machine section, the mechanical advantage is equal to the velocity ratio at any time
:\mathrm{MA} = {v_\text{in}(t) \over v_\text{out}(t)}
:v_\text{in}(t) =  \mathrm{MA}\cdot v_\text{out}(t)
:\Big\|{d\mathbf{x}_\text{in}(t) \over  dt}\Big\| =   \mathrm{MA} \Big\|{d\mathbf{x}_\text{out}(t) \over  dt}\Big\|
:\|d\mathbf{x}_\text{in}(t)\| =   \mathrm{MA} \|d\mathbf{x}_\text{out}(t)\|
Let S_\text{in} be the path the input point follows, and S_\text{out} be the path the output point follows between any time t_1 and t_2.  Let D_\text{in} be the length of S_\text{in}, and D_\text{out} be the length of S_\text{out}.
:\int_{S_\text{in}}\|d\mathbf{x}_\text{in}\| = \int_{S_\text{out}}\mathrm{MA}\|d\mathbf{x}_\text{out}\|
:\int_{S_\text{in}}\|d\mathbf{x}_\text{in}\| = \mathrm{MA}\int_{S_\text{out}}\|d\mathbf{x}_\text{out}\|
:D_\text{in} = \mathrm{MA}\cdot D_\text{out}
:\mathrm{MA} = {D_\text{in} \over D_\text{out}}
:{v_\text{in} \over v_\text{out}} = {D_\text{in} \over D_\text{out}}
--ChetvornoTALK 21:30, 25 November 2017 (UTC)
replies: text: Reverted edits, added supporting citations. --ChetvornoTALK 02:00, 4 December 2017 (UTC)

text: You start by showing that MA is a function of time, and then you integrate assuming that MA is not a function of time.  In general the velocity ratio is not constant.  The integration to obtain a distance ratio requires that the velocity ratio remain constant.  It was exactly this statement that you reverted and have now replaced with an error. Prof McCarthy (talk) 06:18, 4 December 2017 (UTC)
replies: text: I accept your point that in other linkages generally the MA changes with time as the linkage moves, and perhaps that should be mentioned in the article.  But in the 6 Renaissance simple machines, which is what are being discussed in the "Ideal simple machine" section, the MA is constant with time.  That's what I assumed in my proof above, that vin(t) and vout(t) change with time but MA = vin/vout is constant.  In the lever the MA is the ratio of the lever arms; in the wedge and inclined plane it is the slope of the flat bearing surfaces, in the screw it is the lead, in the pulley it is the number of cables supporting the load, and in the wheel and axle it is the ratio of the wheel to axle radius.  In textbooks on classical simple machines "velocity ratio" and "distance ratio" are used synonymously: , , . --ChetvornoTALK 15:20, 4 December 2017 (UTC)
thread_title:  Velocity ratio is equal to distance ratio 

message: In the History section, we have the sentence "He was the first to understand that simple machines do not create energy, only transform it.[16]"
The referenced source does not state this, nor is it a defensible statement. Galileo was apparently the first to describe this fact, but it is unlikely he was the first to conceive of the idea that simple machines do not create energy, and it is impossible to know this for certain unless we can look into the minds of everyone who ever thought about the subject. 
Here is the relevant quote from the source:
″He was the first to explain that simple machines do not create work, but rather alter the way in which work is applied.″ That is not the same sentence, both in that it only claims he was the first to explain, not the first to understand, but also that it refers to work, not energy. 
I suggest either re-wording or perhaps removing the statement. I'm not sure if it adds much, and I'm not sure if Krebs' assertion is reliable anyway. Leperflesh (talk) 21:31, 19 December 2017 (UTC)
replies: text: I think explain in this sentence means assert or state.  If no previous scientist "explained" that simple machines do not create work, then Galileo should be credited with this important breakthrough insight.  And of course "work" is a form of "energy", so in modern terminology what Galileo realized was that simple machines do not create energy. ----ChetvornoTALK 04:51, 21 December 2017 (UTC)
thread_title: Assertion about Gallileo