[paul cotter]

Hamdani's problem is that he cannot conceive of a situation where a force does not initiate motion.

[Bored chemist]

Re "How?"
like this.
The feedback system ensures that the torque exerted by the weight is countered by that produced electromagnetically, and the needle stays in the same place.
Interestingly, his system would be improved greatly by cutting the bottom of the "flag" that shuts of the light at an angle. That way, there would be a small but definite "linear" range over which the light is (roughly) proportional to the angular displacement.


It possible to replace the simple electronics with and A to D converter, a computer, and a D to A converter.
You can then programme the computer to produce any feedback function you chose, including one which is "slightly more than proportional" resulting in the needle actually rising slightly under load.
You could produce a system with an apparent negative stiffness.
This invalidates your assertion about "The finite rigidity of the materials"

For extra marks, try to think of why it would be sensible to introduce such a non-linearity.

It seems to me like you haven't watched the video carefully, or you don't understand how the device that he built works. So, pay attention on the function of photodiode there.

It seems that way to you.
But I have serviced and used such a balance. I think I might have the service manual somewhere.
So it's pretty clear that I do understand it.

Stop assuming you are the clever one here. That's not a view which the evidence supports.
Would you like to tell us what you think is wrong with my viewpoint, in order that we can correct you?

[Bored chemist]

It seems that the function of chatbots is to invent problems where none exist. What a waste of life.

I gather they also waste a few grams of CO2 for each question.
I don't care much how hamdani yusuf wastes his time but...

And then there's this.
https://en.wikipedia.org/wiki/Hallucination_(artificial_intelligence)

[Bored chemist]

In connection with #804, I agree there would be imperceptible movement of the wall but that was not the point- the point was that the force is not cancelled. The rest of the post is abject nonsense. If I fail to turn a rusty bolt, a scenario that has often bedevilled me, I can read off the torque that failed to turn the bolt, ie there is NO cancellation of torque and there is no movement.

Imagine someone is stepping on a weight scale.

Her weight exerts a force down on the scale. The scale reacts by exerting a normal force up with equal magnitude. The total force is zero, thus the woman doesn't accelerate anywhere.

In the case of torque wrench that you described, the measuring part (a needle connected to a spring) is located between the acting force (your hand) and reacting force (bolt thread). The deformation of the spring represent the torque applied, which is equal and opposite to the reactionary torque when the acceleration is zero (after a brief transient period).
In the case where there is an obstructing object right below the middle of the wrench, the opposing force is produced between the acting force and the measuring part. Here, the measurement can show much less value, which is affected by the flexibility of the obstructing object as well as the wrench itself.

You just made it clear that you did not understand the point I made earlier. You can have a scale with an effective negative spring constant.

[Bored chemist]

Hamdani's problem is that he cannot conceive of a situation where a force does not initiate motion.

And, it seems his head would explode if he realise it's possible for a downward force to produce an upward movement.

[paul cotter]

Hi BC, it just goes on and on and on with Hamdani doubling down on his errors oblivious to the inherent contradictions.

[alancalverd]

If radians were formalized as a base unit (e.g., analogous to meters or seconds), rotational quantities would have distinct dimensional identities, resolving ambiguities in units like torque, angular momentum, and energy.

But the radian is a base unit: it's the unit of angle.

The problem here seems to be that nobody has taught the chatbot the difference between units and dimensions. There are no such "ambiguities" - each of these quantities is uniquely defined.

[hamdani yusuf (OP)]

It seems that the function of chatbots is to invent problems where none exist. What a waste of life.

All of the smartest AI models that I have access to have come into a unanimous conclusion. They have allegedly read all research papers that humans have ever written. And they are competing against one another to be the smartest. That should tell you something.

Can you argue against their reasonings instead of committing ad hominem logical fallacy?

[hamdani yusuf (OP)]

Hamdani's problem is that he cannot conceive of a situation where a force does not initiate motion.

Your problem is that you cannot interpret mathematical equations in a physical scenario.
Think about the equation in Newton's second law of motion, F = m.a

[paul cotter]

Newton's second law is fine if there is motion. A force, linear or rotational, can exist without motion and in this case the law does not apply. It is you that cannot grasp the application of formulae.

[alancalverd]

They have allegedly read all research papers that humans have ever written.

Who writes these "research" papers? People who don't understand physics and therefore write e.g. 42 pages of stuff about how illogical it is, or people who use it every day and take it for granted?

Can you argue against their reasonings instead of committing ad hominem logical fallacy?

The common factor in their responses (you can hardly call it reasoning) is a tendency to agree with the questioner. If you ask any slimy consultant "what's wrong with this Stradivarius"  he will point out that the fingerboard is a bit narrow for your chubby fingers. If you ask an expert violinist he will say "nothing of significance, but you need more practice to get the best out of it".

[hamdani yusuf (OP)]

Newton's second law is fine if there is motion. A force, linear or rotational, can exist without motion and in this case the law does not apply. It is you that cannot grasp the application of formulae.

https://en.wikipedia.org/wiki/Force
In physics, a force is an influence that can cause an object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the magnitude and direction of a force are both important, force is a vector quantity. The SI unit of force is the newton (N), and force is often represented by the symbol F.

It seems like you cannot grasp the meaning of counterbalanced.

[paul cotter]

Counterbalanced is fine. Cancellation is not. Answer my question, will the fly under the girls foot be crushed or not? If it is crushed the force is still there, undiminished.

[hamdani yusuf (OP)]

They have allegedly read all research papers that humans have ever written.

Who writes these "research" papers? People who don't understand physics and therefore write e.g. 42 pages of stuff about how illogical it is, or people who use it every day and take it for granted?

Can you argue against their reasonings instead of committing ad hominem logical fallacy?

The common factor in their responses (you can hardly call it reasoning) is a tendency to agree with the questioner. If you ask any slimy consultant "what's wrong with this Stradivarius"  he will point out that the fingerboard is a bit narrow for your chubby fingers. If you ask an expert violinist he will say "nothing of significance, but you need more practice to get the best out of it".

I don't know how the select which research papers to include or exclude in their training data. It's more likely that they were trained mainly from "reputable" sources first, like scientific journals, text books, encyclopedia, or contents from universities official web sites.

I didn't give the AI models any hint. They receive the exact same question and options as the poll of this thread. You can see that their choice is different from mine. You might just feel that way because their choice is different from yours. Or you might be hallucinating about it.

[paul cotter]

Indeed, Alan, I have noticed this too. They rarely if ever disagree with the questioner and frame answers in a way to largely accept the question regardless of how absurd it may be.

[hamdani yusuf (OP)]

Counterbalanced is fine. Cancellation is not. Answer my question, will the fly under the girls foot be crushed or not? If it is crushed the force is still there, undiminished.

It seems like we just disagree on semantics.

Imagine the girl is stepping on the weight scale in an elevator. When the elevator is accelerating up, the weight measured will be more than her rest weight. When the elevator is accelerating down, the weight measured will be less than her rest weight.
When the elevator is free falling, the weight measured will be nearly zero, spare the gravitational attraction between the girl and the weight scale itself.

[hamdani yusuf (OP)]

Re "How?"
like this.
The feedback system ensures that the torque exerted by the weight is countered by that produced electromagnetically, and the needle stays in the same place.
Interestingly, his system would be improved greatly by cutting the bottom of the "flag" that shuts of the light at an angle. That way, there would be a small but definite "linear" range over which the light is (roughly) proportional to the angular displacement.


It possible to replace the simple electronics with and A to D converter, a computer, and a D to A converter.
You can then programme the computer to produce any feedback function you chose, including one which is "slightly more than proportional" resulting in the needle actually rising slightly under load.
You could produce a system with an apparent negative stiffness.
This invalidates your assertion about "The finite rigidity of the materials"

For extra marks, try to think of why it would be sensible to introduce such a non-linearity.

It seems to me like you haven't watched the video carefully, or you don't understand how the device that he built works. So, pay attention on the function of photodiode there.

It seems that way to you.
But I have serviced and used such a balance. I think I might have the service manual somewhere.
So it's pretty clear that I do understand it.

Stop assuming you are the clever one here. That's not a view which the evidence supports.
Would you like to tell us what you think is wrong with my viewpoint, in order that we can correct you?

The feedback system ensures that the torque exerted by the weight is countered by that produced electromagnetically, and the needle stays in the same place. The feedback system can only react to the change of torque AFTER the needle change its position, not before. Thus the torque measurement requires a change in rotational angle, no matter how small it is.

[hamdani yusuf (OP)]

Indeed, Alan, I have noticed this too. They rarely if ever disagree with the questioner and frame answers in a way to largely accept the question regardless of how absurd it may be.

You can ask them yourself about this topic using your own questions. What do they say?

[hamdani yusuf (OP)]

In its answer, Qwen3 rephrased the options from my original poll, and then evaluated each option before finally make a conclusion. What do you think is wrong with its reasoning? What should be changed to make its reasoning correct?

Qwen 3 235B answers.

>
> Looking at the options given in the problem, the user is asking which conclusion is best. The options are:
>
> 1. Current units are perfect.
> 2. Problems exist but no solution.
> 3. Problems exist and there are possible solutions.
> 4. There's a single comprehensive solution.
>
...

### Evaluation of Options:
1. **Option 1 ("Current units are perfect")**: This is demonstrably incorrect, as the issues outlined above are widely recognized in physics and engineering communities. The dimensionless nature of radians and unit overlap are active topics of discussion.

2. **Option 2 ("Problems exist but no solution exists")**: This is overly pessimistic. Numerous proposals (e.g., explicit radians in units, formalizing radians as a base unit) exist to address these challenges, indicating that solutions are both possible and actively pursued.

3. **Option 3 ("Problems exist and there are possible solutions")**: This aligns with the evidence. The ongoing discussions and proposed modifications to unit conventions reflect a recognition of the issues and a commitment to addressing them. For example, the use of radians in torque units (N?m/rad) is already practiced in some contexts to avoid confusion with energy.

4. **Option 4 ("Single comprehensive solution exists")**: This is overly optimistic. While specific solutions (e.g., explicit radians) address particular issues, there is no universally accepted, comprehensive overhaul of rotational units that resolves all challenges. The complexity of physical quantities and their interrelationships makes a single solution unlikely.

### Conclusion:
The most reasonable conclusion is **Option 3**: *The standard units have known problems and there are possible solutions*. This acknowledges the recognized issues (e.g., dimensionless radians, unit overlap) while recognizing the ongoing efforts to refine and improve the measurement of rotational quantities. Proposals such as explicit radians in units and formalizing radians as a base unit represent viable steps toward a more coherent system, even if a single, universal solution remains elusive.

**Final Answer:** 3

[paul cotter]

You have not answered the question, you are trying to avoid it by digressing. Will the fly be crushed?