Why not a Python compiler?

[Bjoern Schliessmann]

Don't cry, I just want to say that I've hated the kilogram-force
almost as much as I've hated the electron-volt. Who is the lazy
who comes up with these things?

eV has a advantages some "kilogram force" hasn't: It's on completely
different order of magnitude. People aren't happy writing 81.8 aJ
(Attojoule = 1e-15 Joule), instead they prefer
511 keV. And the "e" in eV even allows you to leave out the
elementary charge in your calculations most of the time (because
it's already in the unit).

Regards,


Björn

 

[Erik Max Francis]

Don't cry, I just want to say that I've hated the kilogram-force
almost as much as I've hated the electron-volt. Who is the lazy who
comes up with these things?

The electron-volt is a weird little miscreant that ended up becoming
popular. The kilogram-force is a unit that could only demonstrate that
its inventors completely missed the freakin' point.

 

[Jeff Schwab]

Note that Google will give a calculator result for "1 kilogram in
pounds", but not for "1 kilogram in inches". I wonder why not? After
all, both are conversions of incompatible measurements, ie, they
measure different things.

Eh? Last I checked both pound and kilogram are units of mass, so where is
the incompatibility?

I've never heard of "pound" as a unit of mass. At least where I went to
school (Boston, MA), "pound" is the English unit of force, "slug" is the
(rarely used) English unit of mass, and "kilogram" is the SI unit of
mass. ("English" in this context does not refer to the charming isle at
the Western edge of Europe, but to the system of non-metric units used
by most Americans.)

 

[Hrvoje Niksic]

Note that Google will give a calculator result for "1 kilogram in
pounds", but not for "1 kilogram in inches". I wonder why not? After
all, both are conversions of incompatible measurements, ie, they
measure different things.

Eh? Last I checked both pound and kilogram are units of mass, so where is
the incompatibility?

I've never heard of "pound" as a unit of mass. At least where I went
to school (Boston, MA), "pound" is the English unit of force, "slug"
is the (rarely used) English unit of mass, and "kilogram" is the SI
unit of mass.

It would be possible for US pound to only refer to weight, but I
cannot find references to corroborate it. For example, taken from
Wikipedia:

In 1958 the United States and countries of the Commonwealth of
Nations agreed upon common definitions for the pound and the
yard. The international avoirdupois pound was defined as exactly
453.59237 grams.

The "pound-force" wikipedia entry documents "pound" being used as a
unit of force "in some contexts, such as structural engineering
applications."

 

[Jeff Schwab]

-On [20080212 22:15], Dotan Cohen ([email protected]) wrote:
Note that Google will give a calculator result for "1 kilogram in
pounds", but not for "1 kilogram in inches". I wonder why not? After
all, both are conversions of incompatible measurements, ie, they
measure different things.
Eh? Last I checked both pound and kilogram are units of mass, so where is
the incompatibility?

I've never heard of "pound" as a unit of mass. At least where I went
to school (Boston, MA), "pound" is the English unit of force, "slug"
is the (rarely used) English unit of mass, and "kilogram" is the SI
unit of mass.

It would be possible for US pound to only refer to weight, but I
cannot find references to corroborate it. For example, taken from
Wikipedia:

In 1958 the United States and countries of the Commonwealth of
Nations agreed upon common definitions for the pound and the
yard. The international avoirdupois pound was defined as exactly
453.59237 grams.

The "pound-force" wikipedia entry documents "pound" being used as a
unit of force "in some contexts, such as structural engineering
applications."

That's suprising (to me, anyway. We (Americans) all measure our weight
in pounds. People talk about how much less they would weigh on the
moon, in pounds, or even near the equator (where the Earth's radius is
slightly higher). I remember converting pounds to Newtons, and vice
versa, in school. Apparently, what everybody here calls a "pound,"
Wikipedia lists as a "pound-force." But I've only ever heard it called
a pound, if anybody ever used "pound" as a unit of mass at school,
they'd have been laughed at.

http://en.wikipedia.org/wiki/Pound-force

 

[Grant Edwards]

I've never heard of "pound" as a unit of mass. At least where I went to
school (Boston, MA), "pound" is the English unit of force, "slug" is the
(rarely used) English unit of mass,

Back in the day, I was once working on a fire control system
for the Navy. All the units in the calculations were purely
metric except for one: air density was in slugs/m3. I always
suspected that was somebody's attempt at humor.

 

[Jeff Schwab]

Back in the day, I was once working on a fire control system
for the Navy. All the units in the calculations were purely
metric except for one: air density was in slugs/m3. I always
suspected that was somebody's attempt at humor.

So what is the mass of a slug, anyway? (I assume this is slug as in
bullet, not slimy, creeping thing.)

 

[David H Wild]

We (Americans) all measure our weight in pounds. People talk about how
much less they would weigh on the moon, in pounds, or even near the
equator (where the Earth's radius is slightly higher).

Their weight on the moon would be exactly the same as on earth if they used
a balance with weights on the other side of the fulcrum.

 

[Jeroen Ruigrok van der Werven]

I've never heard of "pound" as a unit of mass.

Then please correct/fix:

http://en.wikipedia.org/wiki/Pound_(mass)

Me being mainland European I know not this silly system called imperial.

[Yes, partially in good jest...]

 

[Grant Edwards]

So what is the mass of a slug, anyway? (I assume this is slug as in
bullet, not slimy, creeping thing.)

A slug is 14.593903 kg according to the trysty old Unix "units"
program. Hmm, I always thought a slug weighed exactly 32 lbs,
but I see it's 32.174049. Learn something new every day...

 

[Jeroen Ruigrok van der Werven]

So what is the mass of a slug, anyway? (I assume this is slug as in
bullet, not slimy, creeping thing.)

http://en.wikipedia.org/wiki/Slug_(mass) would be my guess.

 

[Dennis Lee Bieber]

So what is the mass of a slug, anyway? (I assume this is slug as in
bullet, not slimy, creeping thing.)

'Tis neither...

http://en.wikipedia.org/wiki/Slug_(mass)
(and yes, the (mass) is supposed to be part of that URL)
--
Wulfraed Dennis Lee Bieber KD6MOG
(e-mail address removed) (e-mail address removed)
HTTP://wlfraed.home.netcom.com/
(Bestiaria Support Staff: (e-mail address removed))
HTTP://www.bestiaria.com/

 

[Jeff Schwab]

Their weight on the moon would be exactly the same as on earth if they used
a balance with weights on the other side of the fulcrum.

That's true, because they would really be indirectly measuring mass. By
"weight," though, most people mean the force exerted by gravity.

 

[Dotan Cohen]

Their weight on the moon would be exactly the same as on earth if they used
a balance with weights on the other side of the fulcrum.

That is not measuring weight. That is measuring mass. To measure
weight, you need a set, nonvariable reference, such as a spring.

Dotan Cohen

http://what-is-what.com
http://gibberish.co.il
×-ב-×’-ד-×”-ו-×–-×—-ט-×™-ך-×›-ל-×-מ-ן-× -ס-×¢-×£-פ-×¥-צ-ק-ר-ש-ת

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

 

[I V]

experience. The notion of impetus -- where an object throw moves in a
straight line until it runs out of impetus, then falls straight down --
is clearly contrary to everyday experience of watching two people throw
a ball back and forth from a distance, since the path of the ball is
clearly curved.

It's clear _to us_ because when we think about such things, we think in
Newtonian terms. I'm not at all sure it would have been clear to people
in the middle ages; when you throw a ball, it whizzes by so fast, it's
hard to be sure how it's actually moving.

 

[Erik Max Francis]

A slug is 14.593903 kg according to the trysty old Unix "units"
program. Hmm, I always thought a slug weighed exactly 32 lbs,
but I see it's 32.174049. Learn something new every day...

It's defined so that 1 slug times the acceleration due to gravity is a
pound. The acceleration due to gravity is only approximately 32 ft/s^2,
so you were just remembering the short-hand approximation for 1 gee.

Let's hear it for incoherent unit systems ...

 

[Erik Max Francis]

It's clear _to us_ because when we think about such things, we think in
Newtonian terms. I'm not at all sure it would have been clear to people
in the middle ages; when you throw a ball, it whizzes by so fast, it's
hard to be sure how it's actually moving.

Hence why I suggested standing back from two people throwing it back and
forth. If they lob it high, it's hard to miss that the pass is curved.

 

[Erik Max Francis]

It would be possible for US pound to only refer to weight, but I
cannot find references to corroborate it. For example, taken from
Wikipedia:

In 1958 the United States and countries of the Commonwealth of
Nations agreed upon common definitions for the pound and the
yard. The international avoirdupois pound was defined as exactly
453.59237 grams.

The "pound-force" wikipedia entry documents "pound" being used as a
unit of force "in some contexts, such as structural engineering
applications."

Then there's the even more fun and games in contexts where a distinction
between mass and weight is not bothered to be drawn at all. It's more
common in practical engineering matters than pure physics; this is, for
instance, why rocket motor performance (specific impulse) is measured in
seconds, as it's the ratio of the the thrust (force) to rate of fuel
usage (would be mass divided by time, but weight on Earth is used
instead of mass).

Basically, physics rationalizations of Imperial/English/American
(whatever you choose to call them) units are a total mess.

 

[Steven D'Aprano]

It's clear _to us_ because when we think about such things, we think in
Newtonian terms. I'm not at all sure it would have been clear to people
in the middle ages; when you throw a ball, it whizzes by so fast, it's
hard to be sure how it's actually moving.

If they asked an archer to fire an arrow through a distant window, he'd
aim slightly above it. You can't spend dozens of hours every week
shooting arrows at targets without learning to compensate for gravity.

The theory of impetus went through a number of variations over the
millennia. Despite the unsourced diagrams on the Wikipedia article (see
the Talk page for more details) the usual medieval view of impetus was in
the context of ballistics: an arrow or other projectile was fired up at
an arrow, it traveled mostly in a straight line, then slowly curved away
as the impetus was lost and gravity took hold, and then finally dropped
straight down.

http://en.wikipedia.org/wiki/Theory_of_impetus

While it isn't a good model for arrows and cannon balls, it's actually
not too far off the real-world case of a light projectile in the face of
air resistance.

We can be sure that Aristotle was not a juggler, or spent much time
watching jugglers. If he was, he never would have come up with the
impetus theory in the first place.

 

[greg]

rocket motor performance (specific impulse) is measured in
seconds, as it's the ratio of the the thrust (force) to rate of fuel
usage (would be mass divided by time, but weight on Earth is used
instead of mass).

Which is particularly ironic, as you'd think that
rocket engineers, of all people, would be acutely
aware of the need to avoid confusing force and
mass!