Mass vs Mass as a Force (Weight)

[BvU]

I really don't see the problem. Can we please please close this thread ...

$\$

 

[Digcoal]

Ironically, even if basic physics knowledge of mechanics, electricity and thermodynamics was needed to enter a medical school (in my native country, but perhaps in other countries as well), all forms and medical parlance use the word "weight" in the documents to be completed by the general public. That is because there is probably a law/regulation somewhere which states that people need to provide their known weight in kilograms/pounds, because the general public is assumed to be too uneducated to recognize that the weight is really a force (measured in Newtons or lbf), while kilograms/pounds could only refer to a mass (rest mass, but that's taking it to extremely pedantic).

So all of this apparent or real confusion, and threads such as these here, and other places on the internet, because people are assumed not to have studied basic physics and pre-High school or HS. Assumption of ignorance.

I am deeply passionate about linguistics in general, and etymology and grammar, in particular. Also in this domain, it is said that the less educated dictate how a language is developing. This saddens me, really.

My thoughts exactly.

Langauge has a single purpose, and that is to convey an idea from one mind to another. Without agreement, we are left to constantly learn how each individual defines a particular word which bogs down communications and progress.

Mathematics is a language.

 

[Digcoal]

A kilogram always refers to mass in the everyday world too*.

The confusion does not arise because in the day to day world 'people' use kilograms as a measure of weight, the confusion arises because because in the everyday world 'people' use the word weight when they actually mean mass.

When the doctor says 'you need to reduce your weight' he doesn't expect you to achieve this by taking the elevator/lift down a few floors or taking up space flight. When you buy 5 pounds of potatoes you make sure the shopkeeper waits for the scales to settle after tossing the potatoes in, rather than accepting the greater weight of the potatoes as they decelerate in the pan.

* Edit: I can think of one example where this is not the case: ropes and other lifting equipment are almost always specified in kg (or tonnes): there is obviously a safety issue here: it would be easy to think that a 1000N sling was 10 times as strong as it actually is.

When you "weigh" something down, that requires mass and gravitational acceleration. This implies a force, not an amount of matter.

 

[jbriggs444]

When you "weigh" something down, that requires mass and gravitational acceleration. This implies a force, not an amount of matter.

I come down pretty strongly on the descriptivist view of language rather than the prescriptivist point of view.

The operational definition of "weight" in commerce is mass. That is not an implication. That is a fact.

 

[Digcoal]

I come down pretty strongly on the descriptivist view of language rather than the prescriptivist point of view.

The operational definition of "weight" in commerce and medicine is mass. That is not an implication. That is a fact.

Then being “weightless” in space means being “massless”?

 

[jbriggs444]

Then being “weightless” in space means being “massless”?

Words mean different things in different contexts. That too is a fact. One which we may bemoan or celebrate, certainly. But one with which we must live.

We do not do much weighing of goods in space, so the commercial definition of weight is currently irrelevant in orbit. If we were engage in commerce in space, one suspects that the relevant measurements would be of quantity of matter rather than force exerted on deck plates.

 

[Digcoal]

Words mean different things in different contexts. That too is a fact.

Which is the point. The nomenclature is convoluted creating plenty of instances for conflation and confusion.

Hence this post.

And we have a term that is never ambiguous and is invariant to the context for “an amount of matter”: mass.

 

[jbriggs444]

Which is the point. The nomenclature is convoluted creating plenty of instances for conflation and confusion.

Hence this post.

And we have a term that is never ambiguous for “an amount of matter”: mass.

Indeed we do. We, as members of the physics community are certainly free to use that word. And we do.

The English-speaking merchants of the world are equally free to continue to use the word "weight" in the way they have historically done -- a way that amounts to an operational definition of mass. And they do.

 

[Digcoal]

Indeed we do. We, as members of the physics community are certainly free to use that word. And we do.

The English-speaking merchants of the world are equally free to continue to use the word "weight" in the way they have historically done -- a way that amounts to an operational definition of mass. And they do.

Nobody is making a freedom/tyranny point.

This is strictly a matter of logic.

 

[cmb]

* Edit: I can think of one example where this is not the case: ropes and other lifting equipment are almost always specified in kg (or tonnes): there is obviously a safety issue here: it would be easy to think that a 1000N sling was 10 times as strong as it actually is.

FWIW, all the new straps and slings I have seen recently in the last few years are now given in daN .. decaNewtons.

It's one of those 'adapt-a-SI-unit' type that brings a compound SI unit into harmony with existing usage.

Hence, "100 daN" is the 'weight force' of 100 kg.

 

[jbriggs444]

Nobody is making a freedom/tyranny point.

This is strictly a matter of logic.

Langauge choice is dictated by history and convenience, not by logic.

 

[Digcoal]

Langauge choice is dictated by history and convenience, not logic.

And just as synaptic pruning is a natural process for removing extraneous synapses, society also has a natural tendency for such efficiency.

Stating that something irrational is so because of “history” seems quite antithetical to the scientific method.

 

[jbriggs444]

And just as synaptic pruning is a natural process for removing extraneous synapses, society also has a natural tendency for such efficiency.

Stating that something irrational is so because of “history” seems quite antithetical to the scientific method.

Words are used as they are used. We do not get to pick how speakers use them.

Saying that a word does not mean what it is used to mean and what it is understood to mean is the height of irrationality.

Again, I am a descriptivist, not a prescriptivist.

 

[Digcoal]

Words are used as they are used. We do not get to pick how speakers use them.

Saying that a word does not mean what it is used to mean and what it is understood to mean is the height of irrationality. Your stance here appears irrational.

Again, who said anything about “picking how speakers use them?”

Perhaps my stance seems irrational to you because you keep responding to things nobody has said?

 

[Digcoal]

Words are used as they are used. We do not get to pick how speakers use them.

Saying that a word does not mean what it is used to mean and what it is understood to mean is the height of irrationality.

Again, I am a descriptivist, not a prescriptivist.

Be whatever you want, and enjoy explaining irrational use of words.

 

[jbriggs444]

Again, who said anything about “picking how speakers use them?”

Perhaps my stance seems irrational to you because you keep responding to things nobody has said?

Possibly I am confused. You seemed to be arguing that "weight" always means force and claiming that this is a logical consequence... of something.

Is that not your position?

 

[Digcoal]

Possibly I am confused. You seemed to be arguing that "weight" always means force and claiming that this is a logical consequence... of something.

Is that not your position?

Nope. It has never been my position.

I said at the very beginning that I suffered through the exact same confusion as the OP. This whole time I have been explaining why it’s such a pointless and convoluted mess absolving the OP of any fault for dysfunctional language.

I’ve understood the disparity for over a decade.

 

[Digcoal]

Grams is used as a WEIGHT measurement outside of the science community and in everyday life.

The problem arises when we used the same TERM to define MASS.

In imperial measurements, pounds is a measurement of force/weight and slug is a measurement of mass.

This is why science uses Newtons for force/weight and grams for mass.

If there were as hard a push to use Newtons on scales instead of kilograms as there is to push for the use of metric over imperial measurements, your confusion would not occur. I am sympathetic to your plight because I had the same issue reconciling the two ideas a decade ago.

I believe this was my initial comment...

 

[jbriggs444]

Again, who said anything about “picking how speakers use them?”

Perhaps my stance seems irrational to you because you keep responding to things nobody has said?

I have not accused you of irrationality.

It seems that you have accused me of such. You apparently find it irrational to justify the way "weight" is used in practice in commerce.

 

[Digcoal]

I have not accused you of irrationality.

It seems that you have accused me of such. You apparently find it irrational to justify the way "weight" is used in practice in commerce.

I find it irrational to use a term to mean force in some contexts and mass in others when we have terms for both already.

 

[jbriggs444]

I believe this was my initial comment...

Outside the physics classroom, the word "weight" is not automatically a synonym for "force of gravity".

You may find it confusing. Me too. You may see it as being irrational. However, it is nonetheless true. And perfectly rational.

What is irrational is the fallacy of equivocation.

 

[Digcoal]

Outside the physics classroom, the word "weight" is not automatically a synonym for "force of gravity".

You may find it confusing. Me too. You may see it as being irrational. However, it is nonetheless true. And perfectly rational.

Yes. This is what “depending on context” means.

I am happy we agree.

I am sure you can find other instances of people “truly” saying something while that statement is also irrational.

I, for one, am glad we disabused most of society of the notion that the Earth is flat.

 

[jbriggs444]

I, for one, am glad we disabused most of society of the notion that the Earth is flat.

A claim that the Earth is flat is something that can be addressed experimentally. We can run tests with telescopes, Foucault pendula, lasers, satellite pictures and such. Yes, we can agree that flat-earthers are irrational (or ignorant or both).

A claim about what the word "weight" means is not something that can be tested in the lab. The relevant experiments would involve visits to the library, standing on street corners and browsing the Internet to see how the word is used. Not everyone who uses the word "weight" to mean what we would call "mass" is irrational to do so. I think we can agree on this as well.

 

[Digcoal]

A claim that the Earth is flat is something that can be addressed experimentally. We can run tests with telescopes, Foucault pendula, lasers, satellite pictures and such. Yes, we can agree that flat-earthers are irrational (or ignorant or both).

A claim about what the word "weight" means is not something that can be tested in the lab. The relevant experiments would involve visits to the library, standing on street corners and browsing the Internet to see how the word is used. Not everyone who uses the word "weight" to mean what we would call "mass" is irrational to do so. I think we can agree on this as well.

Again, I am not arguing what “weight” means in different contexts.

The point is that it is irrational to use the same term in two different contexts to mean two different things.

If it helps you, imagine programming a computer to communicate using your convoluted language. Imagine how many if-then statements you would need to differentiate between the different uses for it. It requires more lines of LOGICAL code because it is an ILLOGICAL language structure.

What I am NOT claiming:
•Weight/Weigh mean the same thing regardless of context.
•People do not use weigh/weight differently depending on context.
•People need to stop using irrational language despite a desperate need to maintain some arbitrary status quo.

What I am arguing:
•Posts like these are perfectly understandable because it is an illogical use of terms.

“We have always done it that way...” is seldom proof that something is logical.

As I said before, your brain has a natural tendency to prune extraneous ideas when learning because it is LOGICAL to do so.

 

[dextercioby]

[...]

The point is that it is irrational to use the same term in two different contexts to mean two different things.
[...]

That is exactly my point made above about "languages being driven by the less educated". Because the general public is ignorant of how the word "weight" is used by people knowledgeable of physics, it gets used with other meaning on a daily basis. For doctors and merchants "weight is mass", for me "weight is a particular type of force, hence an effect of interaction between bodies".

 

[JT Smith]

The point is that it is irrational to use the same term in two different contexts to mean two different things.

Why is that irrational?

 

[hutchphd]

Wow.

 

[cmb]

...
The point is that it is irrational to use the same term in two different contexts to mean two different things.
...

This is one of those self-disproving types of statement.

So, @Digcoal, tell me about irrational numbers, right?

;)

I believe at this sort of point, normally one is meant to say 'context is everything'.

I buy a massive kilo bar of chocolate, I eat it, and then I go put on pounds of weight! lol

 

[Digcoal]

This is one of those self-disproving types of statement.

So, @Digcoal, tell me about irrational numbers, right?

;)

I believe at this sort of point, normally one is meant to say 'context is everything'.

I buy a massive kilo bar of chocolate, I eat it, and then I go put on pounds of weight! lol

I see you want to conflate psychology and mathematics by attempting to draw an equivalency between mass/force/weight (all physical properties) and irrational (psychological and mathematical).

Let’s explore that shall we?

what is “i”? Imaginary? Well, all numbers are imaginary. All words are imaginary as well. Every single thought that you have is imaginary. Colors, odors, sounds, flavors, textures...all imaginary. Irrational numbers? Why? Because particular numbers don’t think logically, or because their existence is illogical? I am a little less critical of words being used in completely different contexts because it is far easier to distinguish meaning in completely different fields of study.

Weigh and weight and weightless are all used differently within the same field of study.

If you would like, point me to a thread in which somebody is confused about irrational arguments and irrational numbers. I will explain it to them as well.

And where do you purchase chocolate that is under 1,000 times Earth’s atmospheric pressure?

 

[Digcoal]

That is exactly my point made above about "languages being driven by the less educated". Because the general public is ignorant of how the word "weight" is used by people knowledgeable of physics, it gets used with other meaning on a daily basis. For doctors and merchants "weight is mass", for me "weight is a particular type of force, hence an effect of interaction between bodies".

Moreover, where is “weight” used outside the context of gravity? Balance and bathroom scales are designed to function with masses under acceleration, and gravity is the acceleration almost always used by humans to determine mass.