Author Topic: Force multiplier  (Read 33965 times)

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Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #225 on: February 11, 2023, 04:04:50 am »

And what is the source of this stored energy?  Please explain why this source cannot be used directly, without the intermediate energy storage / discharge (stick / slip).  This is a critical point which you persist in ignoring.  This sounds like a religious axiom for you: unprovable and must be accepted on faith.

The source is the treadmill.  Treadmill can only push the vehicle in the same direction that treadmill moves and you need an energy storage device if you want to move in the opposite direction.
I'm not a religious men and I do not accept anything based on faith. The experiment's I made fully confirm what I'm saying.

Offline Nominal Animal

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Re: Force multiplier
« Reply #226 on: February 11, 2023, 04:51:05 am »
The title of this thread is force multiplier as that is your explanation of how this vehicle could move to the right.
No, my explanation of how this vehicle moves to the right is described by simple kinematics, and requires no "force multiplier" or anything like that.

So you either disagree that 3 points are needed and then provide a real world device that I can buy that will do that (like a force multiplier wrench) or you specify what is the third point since I do not see one in diagram (a).
No, that is a loaded question.

Either you admit your understanding is wrong because others have proven it to be wrong, or you are a troll who gets their rocks off by misleading people into magical thinking and idiocy.  Which one will you do?
 

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #227 on: February 11, 2023, 05:13:22 am »
No, my explanation of how this vehicle moves to the right is described by simple kinematics, and requires no "force multiplier" or anything like that.

No, that is a loaded question.

Either you admit your understanding is wrong because others have proven it to be wrong, or you are a troll who gets their rocks off by misleading people into magical thinking and idiocy.  Which one will you do?

It just seems to me that you are ignoring physics and reality.  Reality is not described by kinematics.
Kinematics definition from Oxford Languages
"the branch of mechanics concerned with the motion of objects without reference to the forces which cause the motion."

To elaborate on the definition is that with kinematics you can understand the way an object can move if you can have any forces you want acting on all parts of that object.

This particular example has only one force acting on it and that force is applied between the ground (reference) and input wheel.
The output wheel is the only other contact point and that is also connected to ground.
So there is a force applied between the input and output of this object (basically a floating body gearbox).

There is no proof for your claims and all experiments are in accordance with my explanation. I see no deviation or thing that is not explained by energy storage plus stick slip hysteresis.

Others seem to disagree with you and insist on the force multiplier theory. I will say that that is wrong because of the floating body your kinematics only no force involved theory is much more ridiculous.
If there is no net force the vehicle will not move. How you get that net force is the main question and not what are the degrees of freedom for this vehicle.
I showed this same vehicle moving in both directions with the same applied force by only manipulating the amount of friction on the input and output wheels.
I also explained how it works in both cases. The fact that you can not understand will not make you true unless you provide a proper explanation for both cases and why movement is only possible if wheels are allowed to slide.

In your kinematic model there is no slip as you can assume forces will act against the vehicle body without the need to explain where those magic forces come from.

Offline Nominal Animal

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Re: Force multiplier
« Reply #228 on: February 11, 2023, 05:42:54 am »
I just think there is some brain limitation that makes you unable to understand the correct explanation of how this sort of vehicle works.

Anyone reading this thread now or in the future needs to understand that the "you" highlighted in the above sentence refers to the whole world of physicists and engineers other than electrodacus. That somehow electrodacus has a unique understanding that the whole rest of the world lacks, and that the whole rest of the world has some kind of brain limitation that prevents them understanding what only electrodacus can see.

Anyone reading this thread then has to consider how likely is it that the above situation is true?
Especially since some of us actually have done physics research for a living, applying Newtonian mechanics every day for years; and always with the core understanding that garbage fed into the models yields garbage results, so that the very first examination of any model or result set is always Does this make any sense?  How does this make sense, if it does?

I have a background in physics research, centered at materials physics, but because I particularly enjoy making tools for other researchers, actually extending to quite a various subfields of physics.  I've always been interested in mechanisms and how they work, and modeling their behaviour.  I could write a few self-aggrandizing but verifiably correct (and occasionally funny, because it all would start at childhood, almost half a century ago – I even built my first hut before puberty, with others laughing how ramshackle it looked, and laughing even more when they found out how sturdy it actually was!) paragraphs on exactly why the structures in my brain are actually quite well suited for physics and science and scientific analysis and analysing mechanisms, way more so than average physicist or engineer; but the simple truth is that I've done so quite a bit, successfully, in many subfields, in both the real world and when helping others with actual peer-reviewed physics research.  Tested and found reliable enough, in other words.

The proper understanding of this stuff is important to me.  There are situations when you need analogs and an intuitive understanding instead of exactly correct understanding, and situations when an exactly correct understanding and model are needed.  This is why I do not refer to authority or "laws" nearly as often as others do, because I don't care if people are exactly correct: it suffices their understanding is reliable and allows them to extrapolate and integrate additional information without getting confused.

(The cases where I've made errors do haunt me.  I could discuss the time when I realized I had confused chitin and keratin (former being a polysaccharide and the latter a protein), simply because they have very similar properties and similar names; or the time I realized I had remembered the typical geostationary orbit elevation wrong by a factor of 1000.  I do make errors, but it is important to me I admit them, because leading others astray does actual harm, whereas admitting making an error only feels bad and hurts ones ego.)

This is also why I strongly oppose incorrect modeling (picking a few random forces, and claiming they describe the system, when they clearly do not), and prefer to start at kinematics, which is much easier to understand, and harder to get wrong.  Understanding is not achieved by convincing others; it is achieved by making testable hypotheses, applying ones understanding, and comparing the results to the real world observed results.  Because of this, I find Popperian falsifiability a more valid approach to science than basic verifiability.  It is also exactly why instead of posting a video, I posted the exact description/recipe/model of a vehicle anyone can build and reproduce the findings: no need to take my word for truth, here is how you can find out for yourself.

I know now I cannot help electrodacus understand, no matter how much effort I spend, but I do hope I've helped anyone else reading this thread to not be convinced by electrodacus' physically daft but linquistically clever writings.  On the surface, it looks so reasonable; but if you examine the questions and answers, you can see the lack of logic, rationality, and any kind of scientific rigor: only the opposite, a religious stance on incorrect assertions that no proof will ever shake.

:horse:
« Last Edit: February 11, 2023, 05:46:31 am by Nominal Animal »
 

Online SiliconWizard

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Re: Force multiplier
« Reply #229 on: February 11, 2023, 05:56:50 am »
Oh, but does time slip when you're enjoying yourself! :-DD
 

Offline Nominal Animal

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Re: Force multiplier
« Reply #230 on: February 11, 2023, 06:48:24 am »
"If there is no net force the vehicle will not move."

A net force will accelerate a vehicle, not "keep it moving".  Completely ignoring Newton's first law of motion, and accusing others of not understanding physics, is utterly, religiously, strange.

:horse:
 

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #231 on: February 11, 2023, 07:41:28 am »
This is also why I strongly oppose incorrect modeling (picking a few random forces, and claiming they describe the system, when they clearly do not), and prefer to start at kinematics, which is much easier to understand, and harder to get wrong.  Understanding is not achieved by convincing others; it is achieved by making testable hypotheses, applying ones understanding, and comparing the results to the real world observed results.  Because of this, I find Popperian falsifiability a more valid approach to science than basic verifiability.  It is also exactly why instead of posting a video, I posted the exact description/recipe/model of a vehicle anyone can build and reproduce the findings: no need to take my word for truth, here is how you can find out for yourself.

I know now I cannot help electrodacus understand, no matter how much effort I spend, but I do hope I've helped anyone else reading this thread to not be convinced by electrodacus' physically daft but linquistically clever writings.  On the surface, it looks so reasonable; but if you examine the questions and answers, you can see the lack of logic, rationality, and any kind of scientific rigor: only the opposite, a religious stance on incorrect assertions that no proof will ever shake.

:horse:

Yes kinematics is easier to understand and harder to get wrong but it does not represent reality.

I did not picked random forces as you claim.  There is a single force F1 that is the input to the system. You can not expect any movement if you do not apply any forces. F2 and all others are consequence of the applied F1 so I did not made up forces.

I appreciate you trying to make me and others understand how this works as that is the same thing I try to do.
But kinematics is just not the tool you can use to find how this device works.
No unpowered device will be able to move in the opposite direction of the only applied force without using energy storage.
When have you ever pushed something and thing pushed against you with more force than you applied ?

You claim (let me know if I'm wrong) that vehicle in case (a) can move without any wheel slip ?  But my videos of the real machine shows wheel slip in all cases.
The reason you can justify that is because you are imagining a different setup from that in case (a).
What you imagine is a free wheel treadmill and the applied force between the ground and vehicle body (that will get you exactly what the kinematic model shows and no slip involved).
But the problem in case (a) specifically asks that applied force is provided by the powered treadmill so F1 is applied to input wheel (right)  relative to ground and not relative to vehicle body.
While the result will look very similar with the kinematic model the mechanism involved is very different.
You and it seems most others prefer the simpler kinematic model as it will look to predict the same motion (it is close but not the same) but I think the reality of what happens while more complex (involving energy storage and stick slip hysteresis) is important.


The reason I try to explain this particular device (a) is because people (multiple) have made the claim that it represents the equivalent of the direct downwind faster than wind vehicle when it is in fact representing the direct upwind vehicle and that is because they confuse the input with output.

As for the direct downwind faster than wind, what chance will I have to explain that witch is even more complicated as it involves pressure differential energy storage.
But I can make multiple prediction witch if tested will show the prediction to be super accurate.
For example the claim is that such a vehicle can drive for unlimited amount of time above wind speed and I know that it will start to slow down as soon as it gets to peak speed since at that point pressure differential stored energy will be used up.
Nobody even bothered to take a video from the side on the treadmill model (the one with propeller) to see that acceleration rate drops and not increases as they predict from wrong (invented) equations.
Anything that can be predicted from this vehicle I can predict accurately and I have not seen any real world example of behaviour that is not predicted by my current understanding.

And it seems strange to me that reality (ultimate test of any theory) showing energy storage is ignored or blamed on my setup which is exactly the setup in diagram (a) so the model of interest.  Same with the slip that is also seen in the video.  The locked and dragged example is again ignored.
All this behaviours are explained fully by Newton's laws of motion. My mistake is probably to assume that everyone will be at the same level of understanding as Newton itself because so much time has passed and we tested his theories but human genetics has not changed at all since his time so the amount of people able to understand and not just memorize his discoveries is still very limited.
 


"If there is no net force the vehicle will not move."

A net force will accelerate a vehicle, not "keep it moving".  Completely ignoring Newton's first law of motion, and accusing others of not understanding physics, is utterly, religiously, strange.

A net force is needed for a stationary vehicle to accelerate so increase in vehicle kinetic energy.  An ideal vehicle will then maintain that speed (kinetic energy) without any additional energy input.
A real world vehicle will experience friction meaning that in order to maintain speed (maintain the same kinetic energy) it requires constant input power that ends up as heat.
So if you start form not moving relative to a reference say earth/ground a force needs to be applied relative to earth/ground for the vehicle to move.
You by using kinematics just ignore forces but to get that result you get from kinematics (it is possible) the force will need to be applied to vehicle body relative to ground or to any of the wheels relative to body but it will not work that way if applied force is relative to ground to the wheel on treadmill.

So yes ignoring forces you can get whatever you want but is not the correct description of what happens when force is applied to wheel relative to ground.

Offline Nominal Animal

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Re: Force multiplier
« Reply #232 on: February 11, 2023, 09:19:39 am »
I did not picked random forces as you claim.
You picked two out of all the ones in the system.  How you picked them, I cannot say (and therefore used the term "random"), but they do not constitute any kind of model of the system.

But kinematics is just not the tool you can use to find how this device works.
Yes, it is.  It is telling that you cannot even understand how useful kinematics analysis is.

No unpowered device will be able to move in the opposite direction of the only applied force without using energy storage.
That is utterly wrong.  All you need is a suitable gearing.

The simplest example device is a spool of thread, rolling on its axis on two rails, with the radius of the spool larger than the wheels on the rails (and that is the reason you need the raised rails, as otherwise the spool would touch the ground), and the thread coming off the spool from the underside.  When you pull on the thread, the spool rolls in the opposite direction.

The key is the gear ratio, just like in your vehicle.  When the wheels are on the same axis, it suffices that the driven wheel is larger than the driving wheels.  It is more obvious whenever the ratio of the wheels is large.

When you vary the spool-to-wheel ratio, at certain point you can make it switch directions.  You can also switch directions by having the thread come off the spool from the top, which yields the same behaviour as negating and inverting the spool-to-wheel ratio, as shown by the kinematics math.

Do you want me to show you a diagram of its exact properties and Newtonian mechanics?  Not just kinematics, but all the forces, assuming the device is made of uniform rigid material (say, 3D printed in PLA with 100% infill)?  I can, but would it help?  You probably would just invent some new forces or other inane reasons to not agree with physics and reality.  So, I think it would still be more useful if you tested it yourself.  After all, all you need is two rails and a spindle (an axis with a small wheel, then a spool, and then another small wheel), the wheels much smaller than the spool (say, diameter 1/4 of the sool diameter), and you can clearly observe and test its behaviour yourself.  Heck, if you use a round stick as both the axle and the wheel, it's very simple to do!

In fact, a related device is often used as a physics experiment, with the unspooling thread replaced by gravity.  The wheels form a double cone, bases against each other, apexes outward, and the rails are not horizontal or parallel, but converge downwards.  The ratio of (half of) the rail angle and the conical angle corresponds exactly to the gearbox ratio here.  At 1:1, the vehicle does not move.  At larger than one ratios, the vehicle travels upwards along the diverging rails (because its center of gravity goes down, i.e. it converts potential energy to kinetic energy).  At smaller than one ratios, the vehicle travels downwards along the converging rails (because its center of gravity goes down too).  All this without any kind of initial push.

When have you ever pushed something and thing pushed against you with more force than you applied ?
That is a false simile, and wrong.

You claim (let me know if I'm wrong) that vehicle in case (a) can move without any wheel slip ?  But my videos of the real machine shows wheel slip in all cases.
We are telling you your machine slips because its gear ratio is too close to 1:1, and it suffers from loss of traction.  To fix, you only need to increase the gear ratio.

You refuse, because you axiomatically insist that the gear ratio is irrelevant.  Even after even a simple kinematics analysis shows that the gear ratio is the key factor in describing the behaviour of these vehicles.

Why do you think that one incorrect example is proof that no solution exists?  Even when everyone else is telling you how to correct your example so that it would show the solution you, and only you, claim is impossible?

When did you look at a broken car, and decide that because it didn't work, no four-wheeled car-like device could ever work?
« Last Edit: February 11, 2023, 09:25:58 am by Nominal Animal »
 

Offline cbutlera

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Re: Force multiplier
« Reply #233 on: February 11, 2023, 11:13:33 am »
...
If not convinced by this think about a balance with fulcrum the third point offset as in image below.
Nothing will need to move for the input force to be smaller than output force and Newton's 3'rd law works here as two separate loops with F1 input force having a pair at the fulcrum and the other pair F2 output also relative to fulcrum.
But example a has no 3'rd point the fulcrum equivalent so with that missing input and output force can only be equal.


I can see that now.  Your lever and fulcum example clarifies your understanding of Newton's third law to me quite well.
...

Can you clarify where your think understanding of Newton's third law differs from mine ?
...

In what you wrote above you described Newton’s third law working in loops involving more than two bodies.

To every action, there is always opposed an equal reaction; or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.

The law explicitly applies and only applies to the “mutual actions of two bodies upon each other”, not three bodies in a loop, nor four bodies in a loop, nor any other number of bodies in a loop.

One of your most frequently stated claims in this thread has been that almost everyone who has commented here doesn’t understand Newton’s third law.

I wrote in detail about Newton’s third law in message #37 in this thread, and messages 39, 41, 43, 45, 49, 53, 56, 80, 82, 109, 118, 129, 133, 135, 137, 141, 184, and 188.  Did you really manage to read all of those messages, and not spot the very difference in understanding that you claim to see between almost everyone else and yourself?

You tell us that you want to correct the misunderstanding that most of us have about Newton’s third law.

If you have identified my common misunderstanding then here is your chance, tell me where I am going wrong.  And use the example on the Wikipedia page of the book resting on a table, which is a standard example used when teaching Newton’s third law.  Don’t use an unnecessarily complicated example such as a trolley with a gearbox.  It should be obvious by now to anyone except the most bone-headed, that using that example isn’t going to get the message across. If you can’t explain my misunderstanding using the book resting on the table as an example, then you don’t understand it yourself.

For a long time I have been giving you the benefit of the doubt, but I have reached my troll test moment in this thread.  If you can make a credible attempt to explain why you think that I don’t understand Newton’s third law, using the book resting on a table as the example, then I will continue to participate. If you don't even try, then I too am out of here.
« Last Edit: February 11, 2023, 11:27:07 am by cbutlera »
 

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #234 on: February 11, 2023, 04:11:33 pm »
You picked two out of all the ones in the system.  How you picked them, I cannot say (and therefore used the term "random"), but they do not constitute any kind of model of the system.

The "vehicle" has only two points of contact with the outside world and there is no internal power source (no motor or engine).
So all that is needed to know are the values of F1 and F2 since only those are relevant.  F1 is the input due to treadmill and we need to know what the value of F2 is in relation to F1 to know of there "vehicle" can accelerate in one of this two directions.

Yes, it is.  It is telling that you cannot even understand how useful kinematics analysis is.

Kinematics has some uses but can not be used to predict how the "vehicle" will move in specific conditions like if it had an internal engine appling the force to one of the wheels relative to vehicle body (the part in blue) or if an external force between the ground and vehicle body was applied.

No unpowered device will be able to move in the opposite direction of the only applied force without using energy storage.
That is utterly wrong.  All you need is a suitable gearing.

The simplest example device is a spool of thread, rolling on its axis on two rails, with the radius of the spool larger than the wheels on the rails (and that is the reason you need the raised rails, as otherwise the spool would touch the ground), and the thread coming off the spool from the underside.  When you pull on the thread, the spool rolls in the opposite direction.

The key is the gear ratio, just like in your vehicle.  When the wheels are on the same axis, it suffices that the driven wheel is larger than the driving wheels.  It is more obvious whenever the ratio of the wheels is large.

When you vary the spool-to-wheel ratio, at certain point you can make it switch directions.  You can also switch directions by having the thread come off the spool from the top, which yields the same behaviour as negating and inverting the spool-to-wheel ratio, as shown by the kinematics math.

Do you want me to show you a diagram of its exact properties and Newtonian mechanics?  Not just kinematics, but all the forces, assuming the device is made of uniform rigid material (say, 3D printed in PLA with 100% infill)?  I can, but would it help?  You probably would just invent some new forces or other inane reasons to not agree with physics and reality.  So, I think it would still be more useful if you tested it yourself.  After all, all you need is two rails and a spindle (an axis with a small wheel, then a spool, and then another small wheel), the wheels much smaller than the spool (say, diameter 1/4 of the sool diameter), and you can clearly observe and test its behaviour yourself.  Heck, if you use a round stick as both the axle and the wheel, it's very simple to do!

In fact, a related device is often used as a physics experiment, with the unspooling thread replaced by gravity.  The wheels form a double cone, bases against each other, apexes outward, and the rails are not horizontal or parallel, but converge downwards.  The ratio of (half of) the rail angle and the conical angle corresponds exactly to the gearbox ratio here.  At 1:1, the vehicle does not move.  At larger than one ratios, the vehicle travels upwards along the diverging rails (because its center of gravity goes down, i.e. it converts potential energy to kinetic energy).  At smaller than one ratios, the vehicle travels downwards along the converging rails (because its center of gravity goes down too).  All this without any kind of initial push.
You think that because you do not understand that a gearbox requires 3 point of contact with the outside world in order to be able to do force multiplication.
Any device including your spool example that moves in the exact opposite direction of the applied force requires energy storage and a trigger mechanism like in this cases stick slip hysteresis.
All you need to apply the force to the thread slowly and you will see that you increase the force and spool will not move until a very sharp transition when spool starts to move even as you no longer apply any force but then due to friction the spool will slow down so you need to apply force again.
This sort of behaviour will not exist on a gearbox where input and output force will be continuous as there are no charge discharge cycles.
When you pull on the string the spool will be dragged towards you but it can not move due to static friction at the points where spool contacts the ground.
At some applied force the spool will slip and the elastic energy stored in the wire will make the spool rotate as there is less energy needed to make the spool rotate than to slide towards the applied force.

I will say that a slow motion video will clarify all the above mechanism but I think you will blame the setup and try to find ways to change that other that to acknowledge that energy storage and stick slip hysteresis are involved.
     

When have you ever pushed something and thing pushed against you with more force than you applied ?
That is a false simile, and wrong.

You claim (let me know if I'm wrong) that vehicle in case (a) can move without any wheel slip ?  But my videos of the real machine shows wheel slip in all cases.
We are telling you your machine slips because its gear ratio is too close to 1:1, and it suffers from loss of traction.  To fix, you only need to increase the gear ratio.

You refuse, because you axiomatically insist that the gear ratio is irrelevant.  Even after even a simple kinematics analysis shows that the gear ratio is the key factor in describing the behaviour of these vehicles.

Why do you think that one incorrect example is proof that no solution exists?  Even when everyone else is telling you how to correct your example so that it would show the solution you, and only you, claim is impossible?

When did you look at a broken car, and decide that because it didn't work, no four-wheeled car-like device could ever work?

I will not say that 2:1 is anywhere close to 1:1. I will understand if it was 1.1:1 but not 2:1
No matter the gear ratio one of the wheels will need to slip for the vehicle to move.

But I can give you an example that you can no longer contradict.
Build a 1:1 version and push on the body (apply a force between ground and the body) the vehicle will move exactly how the kinematic model will predict and there will be no slip.
Then take the exact same 1:1 version and pull the paper under one set of wheels (treadmill) and you will see that all you get is slip and no movement.
That will tell you definitively that kinematics can not be applied to predict the motion of the treadmill example as forces are involved and kinematics ignores forces.

Offline fourfathom

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Re: Force multiplier
« Reply #235 on: February 11, 2023, 04:15:38 pm »
Could electrodacus be an evil AI chatbot?  Perhaps not evil, just designed to annoy?
We'll search out every place a sick, twisted, solitary misfit might run to! -- I'll start with Radio Shack.
 

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #236 on: February 11, 2023, 04:29:20 pm »

You tell us that you want to correct the misunderstanding that most of us have about Newton’s third law.

If you have identified my common misunderstanding then here is your chance, tell me where I am going wrong.  And use the example on the Wikipedia page of the book resting on a table, which is a standard example used when teaching Newton’s third law.  Don’t use an unnecessarily complicated example such as a trolley with a gearbox.  It should be obvious by now to anyone except the most bone-headed, that using that example isn’t going to get the message across. If you can’t explain my misunderstanding using the book resting on the table as an example, then you don’t understand it yourself.

For a long time I have been giving you the benefit of the doubt, but I have reached my troll test moment in this thread.  If you can make a credible attempt to explain why you think that I don’t understand Newton’s third law, using the book resting on a table as the example, then I will continue to participate. If you don't even try, then I too am out of here.

The book on the table is to simple of an example to create a proper understanding of Newton's 3'rd law.
The problems with that example are.
1) It involves gravity and it seems all you examples you provided always involved gravity and that will make people think that Newton's 3'rd law only applies in those conditions.
2) No movement is possible so it is always a static example making people think that Newton's 3'rd law only applies to a mechanism that is not in motion.

In any case you isolate the subject and look forces acting on each of them.

A better example of Newton's 3'rd law will be the one in the below image.
I asked multiple times if you can think of a device that will replace the newton meter and will be able to use the input from human to pull the human towards the wall ?


Online IanB

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Re: Force multiplier
« Reply #237 on: February 11, 2023, 06:55:58 pm »
I asked multiple times if you can think of a device that will replace the newton meter and will be able to use the input from human to pull the human towards the wall ?

That question does not have any relevance.

However, we can easily arrange for this to happen:


 
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Offline cbutlera

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Re: Force multiplier
« Reply #238 on: February 11, 2023, 07:47:20 pm »

You tell us that you want to correct the misunderstanding that most of us have about Newton’s third law.

If you have identified my common misunderstanding then here is your chance, tell me where I am going wrong.  And use the example on the Wikipedia page of the book resting on a table, which is a standard example used when teaching Newton’s third law.  Don’t use an unnecessarily complicated example such as a trolley with a gearbox.  It should be obvious by now to anyone except the most bone-headed, that using that example isn’t going to get the message across. If you can’t explain my misunderstanding using the book resting on the table as an example, then you don’t understand it yourself.

For a long time I have been giving you the benefit of the doubt, but I have reached my troll test moment in this thread.  If you can make a credible attempt to explain why you think that I don’t understand Newton’s third law, using the book resting on a table as the example, then I will continue to participate. If you don't even try, then I too am out of here.

The book on the table is to simple of an example to create a proper understanding of Newton's 3'rd law.
The problems with that example are.
1) It involves gravity and it seems all you examples you provided always involved gravity and that will make people think that Newton's 3'rd law only applies in those conditions.
2) No movement is possible so it is always a static example making people think that Newton's 3'rd law only applies to a mechanism that is not in motion.

Well I don’t think that Newton’s third law only applies to gravity, and I also don’t think that Newton’s third law only applies to a mechanism that is not in motion, and I asked you to explain it to me. So those two points do not represent an impediment to using the book resting on a table as an example, when explaining to me, why you think that I don’t understand Newton’s third law.

It’s pretty obvious to everyone that you are unable to do this, and so you chose to throw an irrelevant elephant onto the table instead.

Quote
In any case you isolate the subject and look forces acting on each of them.

No, no, no!  You are confusing it with Newton's first and second laws of motion.  Newton's third law of motion applies to "the mutual actions of two bodies upon each other". It has no relevance to the forces acting on any one body.  Do you understand the difference between one and two?

Quote

A better example of Newton's 3'rd law will be the one in the below image.
I asked multiple times if you can think of a device that will replace the newton meter and will be able to use the input from human to pull the human towards the wall ?



How would the answers of either yes or no to this question have any relevance to Newton’s third law?  Either way, the force exerted by the right hand end of the rope on the hook/elephant, would be equal and opposite to the force exerted by the hook/elephant on the right hand end of the rope. And similarly for the pair of forces between the left hand end of the rope and the man’s hands, and the pair of forces between the man’s feet and the ground, etc.
 

Offline Nominal Animal

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Re: Force multiplier
« Reply #239 on: February 11, 2023, 08:32:46 pm »
Any device including your spool example that moves in the exact opposite direction of the applied force requires energy storage and a trigger mechanism like in this cases stick slip hysteresis.
All you need to apply the force to the thread slowly and you will see that you increase the force and spool will not move until a very sharp transition when spool starts to move even as you no longer apply any force but then due to friction the spool will slow down so you need to apply force again.
Utterly, utterly wrong.

The reason there is a minimum limit to the force required to get the object moving is simply because of stiction, static friction.
There is no slip at all.

A perfect example of this is when you put the object near the edge of a table, with the thread hanging off the table, with a small weight at end.
Small enough weights cannot overcome the static friction, so do not cause the object to move.
The exact weight that causes enough pulling force on the thread to overcome static friction, will cause the object to accelerate at a near constant acceleration¹, because static friction is higher than dynamic friction.  (The force needed to get a rolling wheel moving is larger than the force needed to overcome rolling friction at a constant velocity.  This is due to atomic and molecular interactions.)

¹ Dynamic friction has small components that depend on relative velocities at contact, so the acceleration is not exactly constant; but it is very nearly constant.

The only situation when you see jerky movement of the spool is when you do not keep a constant pulling force on the thread.
In other words, it is you who creates the jerky movement there.  By replacing your jerky pulling with a constant force, the acceleration of the spool is perfectly continuous and approximately constant.

The exact same static friction vs. dynamic friction (especially between rolling components) exists in all gearboxes.

You're just inventing new theories as to why you don't need to test this for yourself, because you know this disproves your theories, and shows it is exactly you who does not understand the physics here.
« Last Edit: February 11, 2023, 08:36:59 pm by Nominal Animal »
 

Offline Nominal Animal

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Re: Force multiplier
« Reply #240 on: February 11, 2023, 09:04:40 pm »
I will not say that 2:1 is anywhere close to 1:1. I will understand if it was 1.1:1 but not 2:1
That is because you do not understand the kinematics here.  Review the math in my reply #92.  In your vehicle, the wheels are the same size, \$r = R\$.  Per your definition, gear ratio \$G = 1/\lambda\$.  Using \$x\$ for the vehicle speed right, and \$y\$ for the treadmill surface speed left, kinematics analysis shows that
$$x = y \frac{\lambda R}{r - \lambda R} = \frac{y}{G - 1} \quad \iff \quad \frac{x}{y} = \frac{1}{G - 1}$$

Let's look at what kind of velocity ratios \$x/y\$ different gear ratios \$G\$ yield:
$$\begin{array}{c|rcr}
G & \frac{x}{y} & ~ & ~ \\
\hline
1:8 & -\frac{8}{7} & \approx & -1.143 \\
1:4 & -\frac{4}{3} & \approx & -1.333 \\
1:2 & -\frac{2}{1} & = & -2.000 \\
1:1.1 & -\frac{11}{10} & = & -11.000 \\
1.1:1 & \frac{10}{11} & = & 10.000 \\
2:1 & \frac{1}{1} & = & 1.000 \\
4:1 & \frac{1}{3} & \approx & 0.333 \\
8:1 & \frac{1}{7} & \approx & 0.143 \\
\end{array}$$
A gear ratio of \$G = 2:1\$ requires the vehicle to move as fast as the treadmill surface.  This requires very good traction, because there is very little torque; only about half the linear force provided by the treadmill surface at the point where the driving wheel contacts the surface.
A gear ratio of \$G = 4:1\$ requires the vehicle to move only one third as fast as the threadmill surface, with so much torque that the linear force in the driving wheel at the point where it contacts surface is three times the force provided by the treadmill surface.

There is a HUGE difference between \$G = 2:1\$ and \$G = 4:1\$, and it is exactly because of the relationship \$x = \frac{y}{G - 1}\$.

That relationship also tells you that changing the gear ratio (from say \$G = 4:1\$ to \$G = 1:4\$) is sufficient to change the direction where the vehicle will move; but because for \$G \lt 1\$ we always have \$\lvert x \rvert \gt y\$, you do need good traction to show that.

That also tells you that with \$G = 1:1\$, this scenario is impossible (no smooth movement with the wheels turning in the same direction), since it is a singular point.  On the other hand, \$G = -1:1\$, i.e. wheels turn the same amount but in opposite directions, yields \$x = -2 y\$, i.e. the vehicle travels in the same direction as the surface of the treadmill, but at twice the speed.  This too requires good traction in the wheels.

You also keep claiming that kinematics is not a good way to analyse such mechanisms, but seeing as I've derived the continuous velocities for any given gearbox, it actually yields testable, verifiable mathematical model of the behaviour of the system.  This is experimentally verifiable stuff.  You just refuse to experiment with it, making all sorts of imaginative excuses as to why you do not need to.

Instead of testing these, you rely on your hand-eye coordination and a single video clip as "proof".  That is not science, it is religion.
« Last Edit: February 12, 2023, 01:40:03 am by Nominal Animal »
 

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #241 on: February 11, 2023, 09:54:32 pm »
That question does not have any relevance.

However, we can easily arrange for this to happen:



So what are you saying exactly ? Will that gearbox be able to move towards the wall ?

Will the human move relative to the wall ?
Will you mind explaining what is inside the gearbox to allow it to move ?
You realize that F1 applied by human equal with F2 at the wall so there is no net force. Not only that but this time there is also no slip posible.

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #242 on: February 11, 2023, 10:06:07 pm »
Quote
In any case you isolate the subject and look forces acting on each of them.

No, no, no!  You are confusing it with Newton's first and second laws of motion.  Newton's third law of motion applies to "the mutual actions of two bodies upon each other". It has no relevance to the forces acting on any one body.  Do you understand the difference between one and two?

You misunderstood what I wanted to say (it is my fault as it was not clear).

When I say isolated I mean you look at groups for two objects (there are a total of 3)
So a pair is book and table and then the other pair is table and ground.


Quote

A better example of Newton's 3'rd law will be the one in the below image.
I asked multiple times if you can think of a device that will replace the newton meter and will be able to use the input from human to pull the human towards the wall ?



How would the answers of either yes or no to this question have any relevance to Newton’s third law?  Either way, the force exerted by the right hand end of the rope on the hook/elephant, would be equal and opposite to the force exerted by the hook/elephant on the right hand end of the rope. And similarly for the pair of forces between the left hand end of the rope and the man’s hands, and the pair of forces between the man’s feet and the ground, etc.

Correct so that also means the that you have the same force on each side of the Newton meter and if you replace that with whatever else you want like a gearbox with input connected towards the human (left) and output towards the wall (right) the forces will remain equal on both sides of the gearbox as the gearbox with a floating body can not do any force multiplication.
But IanB apparently think that is possible based on his answer.
Looking forward to your answer.

Online SiliconWizard

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Re: Force multiplier
« Reply #243 on: February 11, 2023, 10:07:48 pm »
"If there is no net force the vehicle will not move."

A net force will accelerate a vehicle, not "keep it moving".  Completely ignoring Newton's first law of motion, and accusing others of not understanding physics, is utterly, religiously, strange.

:horse:

How can anything accelerate if there is no time, though? :popcorn:
 

Offline Nominal Animal

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Re: Force multiplier
« Reply #244 on: February 11, 2023, 10:14:56 pm »
"If there is no net force the vehicle will not move."

A net force will accelerate a vehicle, not "keep it moving".  Completely ignoring Newton's first law of motion, and accusing others of not understanding physics, is utterly, religiously, strange.

:horse:

How can anything accelerate if there is no time, though? :popcorn:

:-X

Here's the simplest experimental demonstration setup demolishing electrodacus' arguments, using Lego Technic:

Pull the chain left, and the gears rotate clockwise, moving right.  Any motion of the chain corresponds to exactly 0.4× (16:40) movement of the gears right.  With continuous motion of the chain, the motion of the gears right is smooth and continuous.  No slip-stick and no jerking, unless you jerk the chain yourself, jerk.
 

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #245 on: February 11, 2023, 10:15:50 pm »
I will not say that 2:1 is anywhere close to 1:1. I will understand if it was 1.1:1 but not 2:1
That is because you do not understand the kinematics here.  Review the math in my reply #92.  In your vehicle, the wheels are the same size, \$r = R\$.  Per your definition, gear ratio \$G = 1/\lambda\$.  Using \$x\$ for the vehicle speed right, and \$y\$ for the treadmill surface speed left, kinematics analysis shows that
$$x = y \frac{\lambda R}{r - \lambda R} = \frac{y}{G - 1} \quad \iff \quad \frac{x}{y} = \frac{1}{G - 1}$$


Instead of testing these, you rely on your hand-eye coordination and a single video clip as "proof".  That is not science, it is religion.

Before I look at your math please specify how are the two wheels connected in your setup ? Where is the belt connecting them?
Unless I can see that I have no idea what the relation between the two wheels is.

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #246 on: February 11, 2023, 10:23:48 pm »
No slip-stick and no jerking, unless you jerk the chain yourself, jerk.

You may have seen this video but watch closely at second 9  https://odysee.com/@dacustemp:8/120fps24:9
Sorry it is filmed upside down as I used a soldering microscope for the close up ability and high frame rate video recording.
Due to large gear ratio there is only one cycle in the short video with the discharge around second 9.


Explain what happens at second 9 as the motion was constant no jerkines
You can see the zoom out and correct orientation experiment but it will be harder to notice the charge discharge cycles compared to the zoom out video above https://odysee.com/@dacustemp:8/gear-slow30p2:9

Looking forward for your explanation of why tooth engagement suddenly changes at around second 9.

Offline electrodacusTopic starter

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Re: Force multiplier
« Reply #247 on: February 11, 2023, 10:55:21 pm »
That's called backlash. Please stop farming posts with this loony /sci/ stuff.

OK what is the reason for backlash ?  And why it happens at regular intervals proportional with the gear ratio ?
If a gearbox in a normal application will have worked like this at all times it will not have a long life.

In any case this is not a great example and it works due to the tooth shape as it allows the entire assembly to be lifted when force is applied as the axel is not constrained (floating) by anything other than gravity. So gravitational energy storage is used here.
If you were to change the shape of the tooth (will need to be custom designed as it will not be standard) to not allow the gear to be lifted then it will be just locked and not able to move.
I was thinking initially that this will be easier to understand due to reduced number of parts but it is actually more complicated than the case (a) where a belt is used and gravity plays no role other than for the amount of wheel friction.
Elastic energy storage is simpler and more visual and the slip is easier to observe also.


There is an infinite variant of floating gearboxes and all of them will behave the same. I feel that is not constructive to discus all of them as the conversation will never end.
You will have backslash if you have changes in acceleration rate that should let you know that acceleration is not constant meaning the speed of the moving gear assembly is not constant as the movement of the hand is as constant as possible of course will be affected by this charge discharge cycles.
Of course constraint the axle (adin the necessary 3'rd point ) will remove the backlash and it will act as a normal gearbox including force multiplication.
The gearbox assembly is lifted slowly over a long period (charging) then over a much shorter period energy is discharged when the assembly falls back down (what you see as backlash and the definition will be correct).
« Last Edit: February 11, 2023, 11:05:33 pm by electrodacus »
 

Online IanB

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Re: Force multiplier
« Reply #248 on: February 11, 2023, 11:24:11 pm »
So what are you saying exactly ? Will that gearbox be able to move towards the wall ?
Yes, I am saying we can construct a mechanism so that when the human pulls on the rope, the gearbox mechanism moves towards the wall.



Quote
Will you mind explaining what is inside the gearbox to allow it to move ?
You are the smart one here, you figure it out.

I am pretty sure everyone else reading this thread can make a post that says, "I can see how to construct such a mechanism."

Let's see how many do.
 

Offline PlainName

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Re: Force multiplier
« Reply #249 on: February 12, 2023, 12:00:39 am »
I can easily see how to construct such a mechanism.
 


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