## Re: weight vs. mass

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• ... I have a vague recollection from high school chemistry class that there actually is a scientific distinction between mass and weight : Mass is
Message 1 of 5 , Jul 2, 2001
> In normal speech, weight is still the commoner way of expressing what is
> more correctly termed mass. But I've never used it as an equivalent for

I have a vague recollection from high school chemistry class that there
actually is a scientific distinction between "mass" and "weight": "Mass"
is something that is unaffected by gravity, while "weight" depends on
gravity. Hence we say something is "weightless" when it is in orbit, or
that it "weighs" 1/6 (or is it 1/16? some fraction, anyway) of its "normal"
(i.e. earth) weight when it is on the moon. However, its "mass" is the
same, regardless of where it happens to be.

For convenience, the "mass" of any particular body is generally expressed
in the same terms as the "weight" that same body has when here on earth, at
sea level. And, indeed, I suspect that in many contexts this entire
distinction is completely irrelevant.

Nathan Cutler
E = MC^2
• ... there ... Yes, of course, as Simon already explained: To answer the mass-vs-weight query, I was always taught that, strictly speaking, mass is measured in
Message 2 of 5 , Jul 2, 2001
> I have a vague recollection from high school chemistry class that
there
> actually is a scientific distinction between "mass" and "weight"

Yes, of course, as Simon already explained:

"To answer the mass-vs-weight query, I was always taught that,
strictly speaking, mass is measured in grammes whereas weight (being
a force) is measured in Newtons. A man on the moon, for example,
weighs much less than on earth, but his mass is the same regardless
of location (relativistic considerations aside)."

> For convenience, the "mass" of any particular body is generally
expressed
> in the same terms as the "weight" that same body has when here on
earth, at
> sea level.

Actually, what we think of as "weight" is actually mass, not the other
way round. 1kg is a mass, not a weight. A 1kg object has 1kg of
"stuff" in it, and will always have the same amount of "stuff" inside
it, even if it is floating "weightless" in orbit. On earth, 1kg
"weighs" 10N. This means it "pushes down" on the earth with a force of
10 Newtons. But in different conditions it could weigh something
completely different.

> And, indeed, I suspect that in many contexts this entire
> distinction is completely irrelevant.

Yes, of course, in everyday contexts it is irrelevant. However, in a
scientific text (which was what we were discussing), it is more
important to retain the distinction. It could actually be argued (as it
was quite persuasively by my Physics teacher at school) that it's worth
trying to make the distinction in everyday speech as well, in order to
help children to understand the totally different concepts underlying
the scientific definitions (since children often find them extremely
difficult to grasp). I don't know that I'd go that far, because it
seems to me that weight is so much a part of everyday speech, but I do
think it's important not to dismiss the distinction in a scientific
context.

Rachel
• ... Is that a threat? :-) S.
Message 3 of 5 , Jul 2, 2001
--- In Czechlist@y..., "Kostas Zgafas" <kzgafas@t...> wrote:
> Also, don´t mess "weight" with "weights".
>
> K.

Is that a threat? :-)

S.
• S potesenim zjistuji, ze veda je na celem svete stejna. Petr ... other ... inside ... force of ... a ... (as it ... worth ... to ... underlying ... do
Message 4 of 5 , Jul 2, 2001
S potesenim zjistuji, ze veda je na celem svete stejna.
Petr
--- In Czechlist@y..., "Rachel Thompson" <rachel.thompson@s...> wrote:
> > I have a vague recollection from high school chemistry class that
> there
> > actually is a scientific distinction between "mass" and "weight"
>
> Yes, of course, as Simon already explained:
>
> "To answer the mass-vs-weight query, I was always taught that,
> strictly speaking, mass is measured in grammes whereas weight (being
> a force) is measured in Newtons. A man on the moon, for example,
> weighs much less than on earth, but his mass is the same regardless
> of location (relativistic considerations aside)."
>
> > For convenience, the "mass" of any particular body is generally
> expressed
> > in the same terms as the "weight" that same body has when here on
> earth, at
> > sea level.
>
> Actually, what we think of as "weight" is actually mass, not the
other
> way round. 1kg is a mass, not a weight. A 1kg object has 1kg of
> "stuff" in it, and will always have the same amount of "stuff"
inside
> it, even if it is floating "weightless" in orbit. On earth, 1kg
> "weighs" 10N. This means it "pushes down" on the earth with a
force of
> 10 Newtons. But in different conditions it could weigh something
> completely different.
>
> > And, indeed, I suspect that in many contexts this entire
> > distinction is completely irrelevant.
>
> Yes, of course, in everyday contexts it is irrelevant. However, in
a
> scientific text (which was what we were discussing), it is more
> important to retain the distinction. It could actually be argued
(as it
> was quite persuasively by my Physics teacher at school) that it's
worth
> trying to make the distinction in everyday speech as well, in order
to
> help children to understand the totally different concepts
underlying
> the scientific definitions (since children often find them extremely
> difficult to grasp). I don't know that I'd go that far, because it
> seems to me that weight is so much a part of everyday speech, but I
do
> think it's important not to dismiss the distinction in a scientific
> context.
>
> Rachel
• Hi everybody, Would you know, please, what to use for nuceny spravce ? (receiver - according to the dictionary??) Thanks Sabina
Message 5 of 5 , Jul 2, 2001
Hi everybody,

Would you know, please, what to use for "nuceny spravce"? (receiver -
according to the dictionary??) Thanks Sabina
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