Talk:Simple machine

Headline text

Does anyone know exactly what a simple machine is

Should it say "In mechanical engineering" instead of "In physics"? Also, can anyone explain how it is known that there are just these six and no others? Is it just engineering experience, or is a something like a mathematical theorem? Michael Hardy 18:45, 24 Mar 2005 (UTC)

A simple machine is the most basic possible machine that operates on a specific mechanical principle. The pulley, for example, is the simplest way to change the direction of a pulling force without wasting it all (as occurs when you simply pull a rope around a corner). Adaptations of a simple machine are not different machines in themselves, even if they can do things that the basic mechanism does not inherehtly do. A block and tacke, for instance, is an application of the pulley that produces a mechanical advantage although the basic pulley does not. The number of simple machines is defined by the number of known unique mechanical principles.

Despite what so many "experts" say, there are not six principles, which would allow six simple machines. There are four or, if you count Rolamite, five. The four are the inclined plane, lever, pulley, and wheel and axle. Both the screw and the wedge are applications of the inclined plane; and, in fact, the Wikipedia articles on them both so state. Because an application of a simple machine is not a different simple machine, the number is really four. Rolamite, which I include as a fifth simple machine, operates on a principle unlike those of the other four simple machines, and some experts consider it to be a fifth simple machine.

Richard Binder • Pens That Write Right! 23:54, 7 January 2007 (UTC)

Well, you're partly right. The concept of simple machines is intended to identify the lowest common denominators for the transformation of forces. ("Wasting" has nothing to do with it - pulling the rope around a corner is actually an example of an inefficient class 1 pulley.) Inclined planes, levers and pulleys tranform the direction and magnitude of a force. The wheel-and-axle transforms a rotational force into a lateral force and vice versa. The screw also transforms a rotational force but this time into a longitudinal force. Is that sufficient to earn its own "class" as a simple machine? That's an interesting question but neither of our opinions are relevant to the article. Historically, there have been 6 classes of simple machines. The article already notes that some scholars have tried to revise the count but six is still the most commonly accepted list.

Your example of the rolamite is new to me, but on first glance it appears to be in implementation of the wheel-and-axle. The potential applications look fascinating but, Popular Science notwithstanding, I think the jury's still out on whether this will be seen as another simple machine. Rossami (talk) 03:47, 8 January 2007 (UTC)

I think arguing about the number of simple machines is somewhat of a moot point. As was stated above, the designation simple machines arises from engineering, not physics. There is not any "law" in physics that defines a simple machine, but through experience we have developed tools that can easily be utilized to change forces, direction of motion, etc. From reading several articles on wikipedia I've begin to notice how the line between what is science and what is engineering is often blurred, I assume because it in general it encourages education in both areas. Still, I think it is very important to distinguish whether something is a scientific concept or an application of science. I don't know if we need to change physics to mechanical engineering in the article, but I hope people can see the difference. Arsawyer84 16:33, 21 July 2007 (UTC)

Can I suggest that if the 6 examples are indeed a 'classic' list, then we find some references for this, eg physics text books etc. And then the second part of the article can elaborate on how some of them use the same principles. I can't help thinking that the list of the simple machines must rooted quite deep in history, as this would explain why '2pistons+hydraulic coupling' is not included in the list. Jimbowley 13:14, 22 August 2007 (UTC)

Tried to address the issue of the arbitrariness of any list of simple machines by a rewrite in May. Hope it helps --Chetvorno^TALK 12:04, 26 June 2008 (UTC)

hydraulics

Is a hydraulic system a simple machine, independent of the others?

reversed statement on hydraulics because link supplied [1] did not support the statement. My statement may be a bit strong, but I suspect it is a better representation than the previous statement. Hmmmmm. Even if they were included in a few lists somewhere, the inclusion would be 'wrong' so I'm not even sure whether the hydraulics thing should be mentioned at all? Jimbowley (talk) 13:56, 12 December 2007 (UTC)

Hydraulics is the science and the hydraulic press is the simplest possible application of the science in a machine.

The hydraulic press was invented by Blaise Pascal around 1645, and is the latest invention to be potentially included in the list of simple machines. All the other members on the list are thousands of years old.

For a hydraulic press to be a Simple Machine the following must be proved to be true :

a) requires a single force to work

b) performs force transformation (change direction, multiply/reduce force/speed)

c) is not a compound machine (cannot be broken down into simpler Simple Machines)

d) is not a variation on an existing Simple Machine

e) no overzealous application of d) is used (similar to making the Six Simple Machines into only 2 - see main article).

a) and b) are easily true according to most articles on the subject.
c) while a hydraulic Jack is broken into a lever for the handle and a hydraulic press, the hydraulic press itself is typically not broken further down into simple machines.
d) and e) are the tricky requirements.

References for hydraulic press being a kind of Pulley [2]

References for hydraulic press being a kind of lever [3], [4]

References for hydraulic press being a unique Simple Machine [5], [6], [7], [8], [9], [10], [11]

Ambivalent references that mention hydraulic press along with simple machines, but at the same time claim it is not one of the six classical machines. [12], [13], [14]

If the list of 6 classical machines is collapsed into only 2 simple machines [15] then the hydraulic press would belong in the group: lever together with pulley and wheel.

But if we consider the mental leap necessary for jumping from pulley or wheel to lever, then the jump from hydraulic press is of of equal proportion. This would make the hydraulic press a Simple Machine, on the same level as Wheel and Pulley.

Conclusion : The current six Simple Machines are the classical list of Simple Machines, with the hydraulic press being a Simple Machine but not a classical Simple Machine, it being a added in modern time.

Please point out flaws in my (non-original) research, assumptions and conclusions. Jesper Jurcenoks (talk) 04:05, 2 April 2008 (UTC)

Another Unlisted Simple Machine

I suppose that a spring could be regarded as another simple machine, if attachments were made at different points along the spring. Such a spring would convert a small force applied at the end through a large distance, to a larger force applied through a smaller distance at one of the attachments. Some conveyor belts use such a transformation of force of a spring, to avoid shocks in loading.

--Joseph D. Rudmin 18:27, 11 January 2007

What you have described does not actually transform the forces. Springs store and release energy. During release, they apply force identically-opposite to the force applied during storage. The distance over which the force is applied is unchanged. Rossami (talk)

A machine ought to be able to multiply force - "mechanical advantage". A spring is able to multiple Power, that is the energy is released much faster than it is accumulated. A little out of the scope of Basic mechanics, though. Good observation.Pete318 (talk) 23:08, 9 April 2008 (UTC)

Mnemonic?

I don't really see those being mnemonic. They're not, for example, the first letters spelling out a word to make it easier (like the great lakes/homes), or a sentence... The letters supposedly bear a resemblance to their machines, and that's great... except there's nothing else to connect it. "Hmm, I can't remember the simple machines for this test, oh, NOTUVXY! Duh!" It kindof strikes me as original research.... am reminded of having to flag several OR "new and improved calendar" articles. However, I'm not an engineer or anything-- is this taught as a mnemonic, versus something that someone passing by decided to throw in? —The preceding unsigned comment was added by Cantras (talk • contribs) 01:49, August 21, 2007 (UTC).

Yes, it is actually taught as a mnemonic in some old physics texts. I have to agree that I never found it particularly useful but I do remember it being in the book. Perhaps it made more sense in the original Greek or Latin? If someone could verify the history, I think that would be an interesting footnote to the article. Rossami (talk) 03:45, 21 August 2007 (UTC)

Most mnemonics will turn up something on any search engine. Try searching for the musical staff notation (EGBDF) or the resistor colors (BBROYGBVGW). NOTUVXY turns out a total of three hits on google, yahoo returns this very page, etc etc etc... Yngvarr (t) (c) 18:34, 18 September 2007 (UTC)

Number of Simple Machines

There really are only four simple machines. Look at the articles for the wedge, screw, and the incline plane. Essentially, the goals of these three machines are the same and thus they are the same machine. Please note that the screw in itself to be an incline plane but rather the threading around the screw that lets it enter an object. Read the articles on each of these three machines. —Preceding unsigned comment added by 71.53.70.145 (talk) 03:08, 9 September 2007 (UTC)

Many have argued that (and the article already says so). The classic list, however, is of six based on differences in the interpretation of how forces are transformed. For example, you could interpret a screw as a helical inclined plane or you could say that the inclined plane transforms a horizontal force into a vertical force while the screw transforms a rotational force into a longitudinal force. Rossami (talk) 04:44, 9 September 2007 (UTC)

I suppose that this is true. I guess my main quarrel with this article was how it seemed to state that very few people believed there to be only four simple machines. I had believed that the idea should be given a bit more thought. Yet I admit that this annoyance I have is not really all that big. —Preceding unsigned comment added by 71.53.70.145 (talk) 9 September 2007

Citations for the number of simple machines

As has already been discussed extensively above, there is no magic answer for the definitive number of simple machines. However, the classic texts generally list the six shown in the current version of the article. Here are a few quick citations of publications with notes on their counts. Most of these are teacher-support sites aimed at elementary or middle school students and their teachers. I don't consider any of the ones I found to be ideal cites. Better references are requested from anyone who can find them. Rossami (talk) 05:14, 24 October 2007 (UTC)

• The Franklin Institute - 6
• The Science Learning Network - 6
• Scholastic books - 6
• Utah State Office of Education - 6
• Henry County Public Schools, GA - 6
• NASA Glenn Research Center -6
• GSU Physics/Astronomy Dept - 6
• MiKids.com - 6
• Teacher resource cite hosted from Univ of Houston - 6
• EdHeads.org - 7 (includes the gear)
• Boston Museum of Science - 5 (omits the inclined plane)

Note: None of these cites verify the mnemonics that were added to the article back in July 2005. If the mnemonics can't be independently sourced, we should probably pull them out. Rossami (talk)

Thanks for your efforts Rossami, I think we have the same view. We still need a good citation for the 'classic list of six' to prove that there is such a thing. Within the above citations there is plenty of misunderstanding especially on wheel and axle (a wheel on a wagon is not a 'wheel and axle' in the simple machine sense) this is someting I am making my mission to bring clarity to. And the use of a woodscrew as an example of the screw is pretty much 99% missing the point, a car jack (of the vertical screw type)would be a perfect example. Jimbowley 12:43, 24 October 2007 (UTC)

While there is certainly plenty of misunderstanding on this topic, I don't think your two examples are quite it. A wheel on a wagon is still an example of a wheel-and-axle because it is converting the magnitude of force needed to overcome friction at the point of attachment. Consider that without the wheel, the bed of the wagon must be pushed along the floor and will require a certain force (exerted over a given distance) to overcome the friction. With the wheel, the point of friction is moved to the connection between the axle and the wagon (or the axle and wheel hub in the more conventional design). The force you use to push the wagon is increased by the ratio of the radii of the wheel and axle (and the distance moved at the point of connection correspondingly reduced).
On your second point, a bolt would be a better example than a woodscrew because a "normal" woodscrew is simultaneously a simple screw and a wedge. The woodscrew (like the car jack screw) converts a rotational force into a longitudinal force while it is being inserted. That longitudinal force powers the wedge which causes the wood fibers to separate and then to provide friction against the screw. But the difference between a woodscrew and a bolt is not that great to a third grader - and that was the apparent target audience of most of these sites. Rossami (talk) 23:15, 24 October 2007 (UTC)

In reverse order. My example 2, Yes a bolt is better than a screw as an example, but the car jack is much better because lifting a car is understandable to a layman as 'work' where as after doing up a bolt the 'work achieved' is harder to understand (mainly because you can't normally see it).
On whether a wheel on wagon is an example of a simple machine, I can see that I should first persuade you before I tackle the world. This is a little difficult because the wiki pages for simple machine and wheel-and-axle share some of the wrong ideas. anyway, here goes:

Why a wheel is not a machine.

I like to consider lifting objects when thinking about simple machines, in fact I think a useful definition of a simple machine would be that it can help you lift something heavy. However for the purpose of this argument I will use the task of getting a heavy rock from A to B (separated horizontally).
A) We could drag the rock from A to B. This would require considrable effort to be expended.
B) We could attach pulleys to the rock and to a handy tree. The mechanical advantage of this machine means you need to pull the rope less hard (but further) to drag the rock. The same effort is expended.
C) We could spread super slick grease (mu=0.0) along the floor. This would reduce the effort required to a negligible amount.
D) We could attach wheels to rock. This would reduce the effort required to a negligible amount.

The point of these illustrations is that the wheel is like the grease, not like the pulley. The wheel removes the friction that is causing the effort to be expended, it does not give you a mechanical advantage over it.

An important concept is that no 'useful work' has been done in the example above. If we return to the subject of lifting things, we can see that the pulley can help us, but the grease and the wheel are not helpful.
I await comments. I'm sure I can improve my argument if this does not convince. regards. Jimbowley 15:42, 31 October 2007 (UTC)

Your A-D are a great way to explain this. But the wheel is more like a pulley than like grease because, contrary to intuition, the wheel does not remove any friction - it just moves it to a different point and trades distance for force. Friction is a function only of μ, the coefficient of friction (which is an empirical property of the contacting materials) and Fn, the normal force exerted between the surfaces. If you put the rock in a wooden wagon bed, make your wheel, axle and floor all from the same wood with exactly equal smoothness, etc, the coefficient of friction is the same whether between the wagon bed and the floor or between the wagon bed and the axle. And the mass of the rock is unchanged, so the normal force between the wagon and the floor is the same as the normal force between the wagon and the axle. Thus, the force of friction is equal in either scenario. (Now, you can grease the axle and thereby affect μ but for the purposes of this discussion, that would be cheating. Let's continue to assume identical materials. Let's also assume for simplicity that this is a very rudimentary wagon with the wheels fixed to the axle and the axle free to spin within some sort of bracket attached to the underside of the wagon bed.)

To drag the rock from A to B, you must do work equal the force necessary to overcome the friction times the distance travelled - μ Fn (B-A) - because the entire wagonbed travels from A to B, scaping along the floor the whole way.

When you add wheels, the force you apply on the wagon is balanced by the force of the floor on the bottom of the wheel. The force at the bottom of the wheel is transferred into a force applied between the bed of the wagon and the exterior surface of the axle. In doing so, the force is increased in magnitude by the ratio of the radii of the wheel and the axle but is applied over a shorter distance in the same ratio. Since we only have to overcome μ Fn of frictional force at the point of connection, we can use much less input force on the back of the wagon to do so.

Another way to think about it is to consider what would change if you attached a log to the bottom of the wagon instead of a wheel and axle - that is, what if the radii of the wheel and axle were the same? If you nail the log to the bed, you've got wood-to-wood friction (because you're still on the wood floor). If you allow the log to spin within the bracket, you've got wood-to-wood friction of exactly the same magnitude.

Having said all that to defend the "wagon wheel" example, I think that winching the bucket up from the waterwell is a more intuitive example and is much better suited for most classes. Rossami (talk) 20:38, 31 October 2007 (UTC)

On Wheel-and-axle, I added a picture of a waterwell some weeks ago, but used the wrong licence declaration so it got pulled. It may not be the best example anyway because on a waterwell the 'wheel' is usually just a handle and hence does not look like a wheel. I've tried to find an illustration of the wheel and axle that I suspect were used to raise the drawbridge, or raise the portcullis, in a castle. Or maybe I can find an example on a trebuchet.

I see that I need to apply some further argument to persuade you that a wheel is not a machine. I do this not for the sake of winning the argument or to save you from your misconception but to clear the way for me to correct the articles.

Your argument above is based on saying that the wheel does not remove friction but just moves it to a different place. But that is wrong for any example other than your specific wheel/axle/road made of the same material. How does your argument stand up if the wheel has frictionless bearings? Is that a machine still? You said yourself right at the top of this page that 'wasting effort' has nothing to do with it, yet your argument now relies on frictional waste to argue that the wheel is a machine.

Perhaps this confusion is all arising becasue we don't have an agreed definition of 'simple machine' rather we have a historical list but don't know the concept behind the list. For me, a simple machine gives you a mechanical advantage so you can lift stuff, but I'm not sure what makes it 'simple'. Jimbowley 13:46, 1 November 2007 (UTC)

If the wheel, axle or road are made of different materials or if you add bearings, then you are correct that the wheel has the additional effect of changing μ. That does not invalidate the observation that the wheel and axle also transforms forces as a simple machine (though you could argue that if you are simultaneously changing μ that it is now a slightly complex machine).

I think you're right that we disagree over the definition of a simple machine. You are framing it solely in terms of lift. Enabling lifting is a pretty good example but not complete. In classical mechanics, a "machine" is anything which can transform a force in either magnitude or direction. A lever can change the magnitude and/or the direction of a force, whether that force is used to lift a rock up or press a bullet down into a casing or simply to crack a walnut shell (neither up nor down). Likewise, the pulley changes magnitude and direction of a force whether it is vertical (lifting a rock) or horizontal (pulling a ship out to sea). The inclined plane and wedge transform horizontal forces into a vertical forces and vice versa. A screw transforms rotational force into a longitudinal force and vice versa. A wheel and axle transforms a rotational force into a lateral force and back.

The "simple" part is what has always been problematic. In theory, these are the six "simple" machines because they were thought to represent the lowest common denominators - that all other machines could be composed of combinations and variations on these. As the article already says, many people believe that some of the six are not in fact the lowest common denominator - that, for example, the wedge is a variation on the inclined plane. Nevertheless, these are the classic six. Rossami (talk) 05:45, 2 November 2007 (UTC)

I am not saying all machines are lifting devices, just that thinking about lifting is useful when determining whether something is a machine. All the 'simple machines' can be used to help you lift something. Similarly, all the simple machines could be used to help get your bullet into its casing. But a wheel will not help you get a bullet into its casing.

You did not answer my challenge to your argument. What if the wheel has a frictionless bearing? Where is the transformation of forces, that your defintion of machine relies on? (note that this does not imply that I accept your definition of machine, I am simply taking your argumant apart).Jimbowley 14:05, 2 November 2007 (UTC)

As I said above, a wheel with any kind of bearing (frictionless or not) is more than a simple machine. Changing μ is outside the scope of a classic simple machine. It reduces the need for a force, it does not change any force.

A wheel and axle can be used to lift something (or press the bullet into the casing). If you attach a cam to the axle, you can convert a small (rotational) force applied over a longish distance to a much larger force applied over a shorter distance to press the bullet into the casing. And if you attach a rope to the axle, you can winch up the water bucket.

I think that the way you are defining the problem, you are prelimiting yourself to scenarios which require a longitudinal force. That's not how the wheel and axle works. It transforms rotational forces. By the way, this is not "my" definition of a simple machine. That's the standard definition used in classical mechanics texts. Rossami (talk) 15:02, 2 November 2007 (UTC)

All the above info about 'wheel and axle' is irrelevant. We are discussing a wheel, and the example we are using is a wheel on a wagon which. You stated it was a machine because it transforms forces.

When I say 'your definition' that means the definition that you are using in your argument, it does not mean you invented it, and it does not imply that I either agree or disagreee with it.

So please, give me a definition of a simple machine and show how a wheel with a frictionless bearing meets that definition. Or better still, having had plenty of time now to think it through, agree that a wheel is not a machine.Jimbowley 17:25, 3 November 2007 (UTC)

One more machine?

I am curious about why the vector mechanics devices are often ignored. True, the topic of simple machines is usually restricted to undergraduate and even elementary science courses, however the bowstring (in an archer's bow) is both ancient and basic.

Further, an number of (web)sites and articles confuse mechanical efficiency (work out/work in [which should be 1.00 for an ideal machine]) with mechanical advantage, i.e. force out/force in.

142.163.53.194 (talk) 18:25, 11 December 2007 (UTC)(peter)

See the discussion on springs above. A bowstring stores and then releases energy but does not convert the force applied. Rossami (talk) 21:37, 11 December 2007 (UTC)

I should be more specific. The BOW itself (a cantilever spring)stores the energy, the bowstring [a taut cord] bends the bow and stores very little energy itself. When the deflection is minimal a small horzontal force requires large vertical forces in the string to maintain equilibrium.

The crankshaft mechanism at TDC (and BDC) of a crank and slider(piston) assembly exhibits a similar nonlinear mechanical advantage.

With respect to the section on springs:
The helical spring is primarily an energy storage device..... however each coil displays a lever mechanism. A spring with a few coils with a large spring constant is difficult to deflect, however increasing the number of identical coils lowers the spring constant allowing a a greater deflection for the same force. True, it maybe a "stretch"(sorry!) but in that sense it displays the attributes of multple simple machines.

One additional note on simple machines that is also often overlooked is that of the block and tackle. Pulleys are not necessary for mechanical advantage to be achieved - only rings or bars with a low coefficient of friction between the rings and rope. The mechanical advantage is achieved by the number of passes of a constant tension cable.

142.163.53.194 (talk) 22:48, 11 December 2007 (UTC)Peter

You are right. But in the bow application it is just part of a process which may explain why it was not considered worthy. I am currently trying to think of an example where the principle is used to lift something or do some other work as an end result! Jimbowley (talk) 14:05, 12 December 2007 (UTC)

You make a good point - the bowstring mechanical advantage is only part of the mechanism.

If still curious, though, there is a technique used to tighten rigging on ships - mostly tall ships now. The rope in a block and tackle assembly is wrapped around a pin or rail to maintain tension. Then one crew member pulls on one of the pulley ropes as one would with an archer's bow. The blocks are pulled together easier than pulling directly (axially) on the rope. As the rigger releases the bowed cable the other riggers pull in the slack.

Modern riggers now use a gear winch with a rachet mechanism to trim large sails.

A rare application now, but if one scans tall ship videos one is bound to see the technique.

Still, the bow string better displays ( I think) the vector technique than does the variations of the inclined plane.

The application of this technique in compression(as opposed to tension in the bow string) is common in crank and slider designs in manufacting processes such as stamping and pressing.142.163.53.194 (talk) 20:04, 12 December 2007 (UTC)Peter

What you describe I would call a general rigging technique, but there isn't a machine there. For some reason this got me wondering how many people go through life without ever using ropes and knots. Jimbowley (talk) 11:03, 13 December 2007 (UTC)

This tall ship video almost shows this technique: Youtube Video on Barque James Craig added Feb3/07 by "betobatres" 6:56min see frames between 1:40 and 2:00 minutes. [16]Pete318 (talk) 18:30, 10 April 2008 (UTC)

Adding to the variations list

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)

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)

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)

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)

Simple Machine or simple machine

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)

Rolamite

Richard Binder Writes :

There are four or, if you count Rolamite, five.

Binder continues : Rolamite, which I include as a fifth simple machine, operates on a principle unlike those of the other four simple machines, and some experts consider it to be a fifth simple machine.\

Rossami answers :

Your example of the rolamite is new to me, but on first glance it appears to be in implementation of the wheel-and-axle. The potential applications look fascinating but, Popular Science notwithstanding, I think the jury's still out on whether this will be seen as another simple machine. Rossami (talk) 03:47, 8 January 2007 (UTC)

Jesper Jurcenoks answers :

Rolamite is a method to reduce friction, like a roller or a ball bearing, but where is the mechanical advantage ?

A Simple Machine must be able to either a) Transfer direction of a force or b) multiply force or speed, Rolamite is probably a machine, it is certainly simple, but it does not make it a Simple Machine. Jesper Jurcenoks (talk) 23:35, 1 April 2008 (UTC)

"in physics" or "in (mechanical) enginering"

Michael Binder asked :

Should it say "In mechanical engineering" instead of "In physics"?

Arsawyer84 answers :

As was stated above, the designation simple machines arises from engineering, not physics. There is not any "law" in physics that defines a simple machine, but through experience we have developed tools that can easily be utilized to change forces, direction of motion, etc. From reading several articles on wikipedia I've begin to notice how the line between what is science and what is engineering is often blurred, I assume because it in general it encourages education in both areas. Still, I think it is very important to distinguish whether something is a scientific concept or an application of science. I don't know if we need to change physics to mechanical engineering in the article, but I hope people can see the difference. Arsawyer84 16:33, 21 July 2007 (UTC)

Jesper Jurcenoks answers :

After reading the definitions on physics and engineering and mechanical engineering, it seems obvious that Simple Machines does not belong in physics, and definitely in engineering. Mechanical Engineering is a subcategory of Engineering that seems to fit Simple Machines best, but Simple Machines will also find their applications in other subcategories such as Aerospace engineering (wing load is lever), Civil Engineering (bridge is level, suspension bridge is fulcrum and lever etc) Nanotechnology (even very small machines are made of Simple Machines), Mechatronics etc.

So instead of restricting the Simple Machines to only Mechanical Engineering, I believe we should place it in engineering. Jesper Jurcenoks (talk) 00:24, 2 April 2008 (UTC)

Hard to call. The concept of a "simple machine" is alleged to date back to Aristotle. Whether true or not, it pretty clearly predates the modern distinctions between those fields. The only places I've ever seen it taught were elementary school level science classes (again, long before students are ready to learn about the difference between physics and engineering) and Physics 101 texts. I've never seen it in an engineering text. Rossami (talk) 02:18, 2 April 2008 (UTC)

Lastronin suggests :

Would the term mechanical physics do as a compromise? Physics, I believe, is more academic, a study of the human body, whereas engineering is our application of extension. As a matter of emphasis, sometimes I prefer physical mechanics, that is, performed and not on a sheet of paper like a blueprint. In the daily mundane of the vernacular, I prefer to call this motion "exercise" and not "work" or "force" per se. —Preceding unsigned comment added by 68.52.142.197 (talk) 21:11, 8 April 2008 (UTC)

Definition of Simple Machine

Does anyone know exactly what a simple machine is [?] Richard Binder • Pens That Write Right! 23:54, 7 January 2007 (UTC)

This article needs a good simple non-ambiguous definition of a Simple Machine. So that anybody can take a given machine and see if it falls under the definition of a Simple Machine. Definitions like : a Simple Machine is one of the following X machines - Lever, Pulley, ...." will not do, as the definition needs to shows why these X machines are Simple Machines, not just be an arbitrary selection.

I propose the following definition of a Simple Machine :

For a given machine to be a Simple Machine the following must be proved to be true :

a) requires a single force to work (no stored energy see discussion on springs)

b) performs force transformation (change direction, multiply/reduce force/speed)

c) is not a compound machine (cannot be broken down into simpler Simple Machines)

d) is not a variation on an existing Simple Machine

e) no overzealous application of d) is used (similar to making the 6 Simple Machines into only 2 - see main article).

Jesper Jurcenoks (talk) 04:06, 2 April 2008 (UTC)

While certainly a reasonable definition, it is not one that I have ever seen written down anywhere else. It would therefore seem to fall afoul of WP:NOR. Can you cite that definition in some other reliable source? Rossami (talk) 04:24, 2 April 2008 (UTC)

The Proposed definition is a sumary of the most common definitions of Simple Machines found on the web. Definitions of the type : "a Simple Machine is one of the following X machines - Lever, Wedge ..." are excluded from participating in this definition discussion as they only lists Classical Simple Machines from a certain standpoint but does not define why they are on the list.

A proposed definition of a Simple Machine must be able to pass the following test :
Can it be applied to the current list of Simple Machines and correctly identify them according to the new definition.

Requires a single force to work
Some definitions include the "Require a single force to work" in one form or another including this article and the following links : [17], [18] [19] [20] [21] [22]

Performs force transformation
You will see the force transformation in one of many variations in most definitions of a Simple Machine :
Including : It is to move an object from one position to another position. [23]
Makes work Easier [24] [25],[26], [27],
A Simple Machine is a device for increasing forces or changing the direction of a force [28] [29] [30] [31]

Is not a Compound Machine
Since the definition of a Compound Machine is that it is made from 2 or more Simple Machines [32], [33], [34], [35] It goes that any Machine that can be broken down into simpler machines is therefore not a Simple Machine but a Compound Machine. Typical wordings for this require includes : "any of various elementary devices considered as the elements of which all machines are composed" [36] "All Machines are build from one or more simple machines" [37]

It is not a variation of an existing simple machine

The list of Simple Machines are not all the simple machines in the world, but the base form of the simple machines that surround us. Example the "baseball bat" is a 3rd class lever, it is therefore a simple machine in itself, but it is not listed among the classical list of Simple Machines as it is listed under its base form: the lever. The knife is a wedge and the bolt is a screw, a Crowbar is a lever etc.

no overzealous application of d) is used

Simple machines fall into families : currently there are two known families : the Inclined plane family (inclined plane, screw and wedge) and the lever family (lever, pulley, wheel & axle). Most Scholars refers to the families but keep the six machines distinct. Some people place gears as a separate simple machine [38], [39] while other claim that gears are just wheels with teeth.[40]

The last requirement is the hardest to quantify, until somebody can describe a method to measure the distance from knife to wedge, from gear to wheel from wedge to inclined plane and from wheel to lever, we will have to make it a judgment call. Current consensus seems to favor :
That the distance from knife to wedge, from seasaw to lever from bolt to screw is "small" and that they therefore are variations of a base Simple Machine.
That the distance from from wedge to inclined plane, and from gear to wheel is "medium" and therefore could fall into either "Variance of base simple machine" or "distinct simple machine"
That the distance from pulley to lever, from wheel to lever, and from screw to the inclined plane is "large" and therefore these are distinct Simple Machines.
That the distance from pulley to lever is shorter than the distance from pulley to inclined plane, and therefore the pulley belongs to the lever family.
That the distance from inclined plane to lever is "Great" and therefore these are separate families.

Other definitions
It is made of 1 or 2 pieces [[41]] [42]

Excellent Discussion

142.163.53.194 (talk) 16:49, 2 April 2008 (UTC)This is an excellent discussion, especially since April/08.

Part of the problem in deciding on the definition of a "simple machine" is that many students accept the "Six Simple Machines" as doctrine.

Perhaps, as an interim measure, these Six SIMPLE Machines are better referred to as Six SAMPLE Machines. The usual application in education is introducing students to the concept of ANY machine.

Good Show Lads(Lasses(?))!

peter

A Fulcrum, The Human Body

A fulcrum is the simplest machine I have encountered, from which all others act upon, as it is a "point." In other words, it is a manifold collapse (or unfolding) of machines in the plural. But then we get a lot of space junk. A healthy body does not have a lot of junk but requires space for demonstration.

Request for images

On 25 April 2008, Beland added the {{reqdiagram}} 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)

I agree with Rossami, no need for pictures here Jesper Jurcenoks (talk) 13:11, 11 May 2008 (UTC)

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. --Chetvorno^TALK 12:17, 26 June 2008 (UTC)

About the Wedge

In my opinion, the wedge has two distinct purposes, one as an inclined plane and one as a hydraulic. A wedge stuck into a door acts as an inclined plane, turning a horizontal force into a vertical force. An ax, however, is also considered a wedge. When it first strikes a perpendicular surface, it does not rotate any force to other directions. What it does is, like a hydraulic, trade distance for pressure. Consider a piece of wood with a wedge on top of it pointed down, and a cubic weight on top of the wedge. Without the wedge, the weight resting on the wood would apply a pressure equal to its weight divided by the area of one side. With the wedge in place, the weight provides a pressure equal to its weight divided by the very small area of the pointed edge of the wedge. This "concentration of force," if you will, is the entire principle behind blades, which one could consider a form of wedge. But the simple machine most associated with such a concentration is the hydraulic, not the wedge.24.90.235.104 (talk) 14:23, 9 July 2008 (UTC)