[Bored chemist]

Quote from: Bored chemist on 04/03/2025 18:36:30
Pick an ISO standard and try to find out who wrote it.

[Bored chemist]

But someone else do use them and need more consistent units.

Who?

[hamdani yusuf (OP)]

Now suppose you want to calculate α in grad/sec2, or rpm/sec.  This means you will have to define Hamdani torque as something other than just force x distance, depending on what units you want to use for angle. But you exert and measure torque by just hanging a weight on a bar.....

hanging a weight on a bar produces force. Assuming that the system is not in free fall. When no rotation occurs, there's no rotational angle. Thus no net torque.
In case you use torque wrench, there's slight rotation between the lever and its head, which can be used to calculate torque.

[hamdani yusuf (OP)]

But if you use consistent imperial units, foot-pounds and lbm.ft2, or consistent SI units N.m and kg.m2, α is automatically in rad/sec2, just as you were taught in school.

α is automatically in rad/sec2 only if you use second as the base time unit and radian as the base rotational angle. The radian automatically appears because it's defined as the ratio between arc length and radius.
Your school should also introduce other units to compare with SI units.

[hamdani yusuf (OP)]

In the absence of a problem, why invoke a "solution" that only applies to free rotation?

I've explained the problem in my video, also in the table comparing rotational quantities and their linear counterparts. If you can't see it as a problem, may be you've never needed to use those rotational quantities to solve your other problems.
Water pumps normally work against pressure and friction. They are not entirely free to rotate. On the other hand, ignoring the unit of rotational angle in torque restricts its use to stationary systems.

[hamdani yusuf (OP)]

Quote from: Bored chemist on 04/03/2025 18:36:30
Pick an ISO standard and try to find out who wrote it.

Repeating the same sentence over and over again doesn't make it any more useful than they are.

[hamdani yusuf (OP)]

But someone else do use them and need more consistent units.

Who?

At least a dozen scientists between 1936 and 2022 have made proposals to treat the radian as a base unit of measurement for a base quantity (and dimension) of "plane angle".[18][19][20]

Perhaps my Wikipedia quote is too long for you to read and understand it in its entirety. Perhaps it's time for you to consider unloading some of your cognitive tasks to AI assistants.

[hamdani yusuf (OP)]

These incompatibilities can be eliminated by making a distinction between geometric radius and rotational radius. While geometric radius is still measured in meter, rotational radius is measured in meter per radian because it represents the ratio between arc length of the rotational motion and its angular distance.

I think a good indicator that a radius is geometric instead of rotational is if it can still have a defined value while the object is stationary. Rotational radius is only defined when there's a rotation.

 

[Bored chemist]

Quote from: Bored chemist on 04/03/2025 18:36:30
Pick an ISO standard and try to find out who wrote it.

Repeating the same sentence over and over again doesn't make it any more useful than they are.

I'm sorry. I forgot you don't understand implicit questions
I should have said
"How far do you get if you pick an ISO standard and try to find out who wrote it?"

[hamdani yusuf (OP)]

I'm sorry. I forgot you don't understand implicit questions
I should have said
"How far do you get if you pick an ISO standard and try to find out who wrote it?"

I'm sorry if I can't read your mind.
I asked ChatGPT,
Who wrote ISO/IEC 9899?

The ISO/IEC 9899 standard, which defines the C programming language, was written by the ISO/IEC JTC 1/SC 22/WG 14 ? that?s the Working Group 14 under the Joint Technical Committee 1, Subcommittee 22 of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).

The key figures involved included a mix of computer scientists, compiler developers, and industry experts. Some notable contributors were:

Dennis Ritchie ? co-creator of the C language, whose work heavily influenced the early drafts.

P.J. Plauger ? a key contributor to C's standardization and a well-known figure in software development.

Tom MacDonald ? chaired the ANSI committee that developed ANSI C, which served as the foundation for ISO C.

Clive Feather ? an active participant in the C standardization process.

Lawrence Crowl ? contributed to various revisions of the C standard.


The first official ISO standard for C, ISO/IEC 9899:1990 (often referred to as C90), was based on the earlier ANSI X3.159-1989 standard (known as ANSI C). When the C language transitioned from ANSI to ISO, the working group refined it further to make it internationally recognized.

Subsequent versions include:

C99 (ISO/IEC 9899:1999) ? added new features like inline functions, variable-length arrays, and the long long type.

C11 (ISO/IEC 9899:2011) ? introduced multi-threading support and safer standard library functions.

C17 (ISO/IEC 9899:2017) ? mostly a bug-fix release.


The current version (as of the last update) is C23 (ISO/IEC 9899:2023), which brings even more modern features to the language.

Would you like me to dive deeper into a specific version of the C standard or how these working groups collaborate? Let me know!

What's the point you were trying to make? Please make it more explicit.

[alancalverd]

table comparing rotational quantities and their linear counterparts.

There's the problem. According to Newton, linear motion and rotation do not have "counterparts".

And torque does not always invoke rotation. As you pointed out in a couple of earlier posts, that would produce an absurdity.

[hamdani yusuf (OP)]

It's obvious that I'm not the only one who's not satisfied by the current standard units for some rotational quantities for their inconsistencies with each other. The problem has already been identified at least since 1936, although no satisfying solution has been found.

Let's list down all pros and cons of each option for standard units of rotational quantities, so we can easily understand what's at stake here.

Option 0: keep using current standard units.
Pros:
- Nothing needs to be done. Just business as usual.
- Currently existing textbooks can still be used.
- Requires less characters because some unit of angle can be omitted.
Cons:
- It leads inevitably to ghostly appearances and disappearances of the radian in the dimensional analysis of physical equations.
- A perennial problem in the teaching of mechanics, where radian appears on one side of an equation, but not on the other side.
- The typical advice of ignoring radians during dimensional analysis and adding or removing radians in units according to convention and contextual knowledge is "pedagogically unsatisfying".

[hamdani yusuf (OP)]

There's the problem. According to Newton, linear motion and rotation do not have "counterparts".

The table shows they do.

[hamdani yusuf (OP)]

And torque does not always invoke rotation. As you pointed out in a couple of earlier posts, that would produce an absurdity.

The force doesn't always produce torque. You seem to forget about this.

Do you realize that when the rotation of the bolt is slowing down, the rotational acceleration is negative?

What's the torque at the center of the lever?
What's the torque at the bottom of the legs of the bench?

[hamdani yusuf (OP)]

Option 0: keep using current standard units.

Option 1: Change the unit of a radius to meters per radian
Pros:
- Solve the problem from option 0.

Cons:
- Incompatible with dimensional analysis for the area of a circle, πr^2, or volume of a sphere, πr^3.

[hamdani yusuf (OP)]

Option 2: Introduce a dimensional constant.

Pros:
- According to Quincey this approach is "logically rigorous" compared to SI.

Cons:
- Requires "the modification of many familiar mathematical and physical equations".
- It is "rather strange" and the difficulty of modifying equations to add the dimensional constant is likely to preclude widespread use.

[Bored chemist]

Perhaps my Wikipedia quote is too long for you to read and understand it in its entirety.

Interestingly, I think you didn't understand it.
Just twelve physicists, and you, think it needs changing.

What's the point you were trying to make? Please make it more explicit.

You said
"

Is the new standard document anonymous? Or worse, undocumented?

"
as if anonymity is a bad thing.
And it turns out that the ISO standard you chose is anonymous.

Your AI found a few names (and who knows, they may even be correct).
But do you really believe that  ISO/IEC JTC 1/SC 22/WG 14 is only 5 people?
Do you really think it was written by a group of  5 people, one of whom is dead (and another in his 80s)?

The point remains that ISO standards (along with many other standards) are anonymous.

Why do you think anonymity is a problem?

[hamdani yusuf (OP)]

Just twelve physicists, and you, think it needs changing.

The article says "at least", which means it could be more. Not to mention how many have identified the problem, but kept silent for they haven't found a promising solution.

[hamdani yusuf (OP)]

The point remains that ISO standards (along with many other standards) are anonymous.

I just shown a counter example of your assertion.

Why do you think anonymity is a problem?

I don't. Why do you think I do?

https://en.m.wikipedia.org/wiki/Trust,_but_verify

[hamdani yusuf (OP)]

Option 0: keep using current standard units.

Option 1: Change the unit of a radius to meters per radian
Pros:
- Solve the problem from option 0.

Cons:
- Incompatible with dimensional analysis for the area of a circle, πr^2, or volume of a sphere, πr^3.

So, there are cases where the unit of a radius is more appropriate to be expressed in meters per radian, while in other cases, it is more appropriate to be expressed in meters. The next step is to identify the distinguishing characteristics between them.

These incompatibilities can be eliminated by making a distinction between geometric radius and rotational radius. While geometric radius is still measured in meter, rotational radius is measured in meter per radian because it represents the ratio between arc length of the rotational motion and its angular distance.

I think a good indicator that a radius is geometric instead of rotational is if it can still have a defined value while the object is stationary. Rotational radius is only defined when there's a rotation.