Why So Many Units?...

[Clifford Heath]

On 22/7/20 11:33 am, Ricketty C wrote:

On Tuesday, July 21, 2020 at 8:16:30 PM UTC-4, Clifford Heath wrote:
On 22/7/20 5:28 am, Ricketty C wrote:
On Tuesday, July 21, 2020 at 11:52:51 AM UTC-4, Lasse Langwadt Christensen wrote:
tirsdag den 21. juli 2020 kl. 17.18.42 UTC+2 skrev Ricketty C:
On Tuesday, July 21, 2020 at 3:47:40 AM UTC-4, Clifford Heath wrote:
For electric cars, the measure is newtons, the force required to
maintain velocity against drag.
Newton is not useful since it will vary...

More prevarication snipped...

But that\'s not what people actually use. You put kWH into your battery,
you get km out. The ratio of those is in newtons.

You are thinking like some sort of scientist or engineer. Lord, no one cares about Newtons! They care about Wh/mi

No, it\'s miles that no-one cares about. Civilised countries barely even
remember those.

The point of my entry into this thread wasn\'t to remind people what they
already care about. It was to suggest a different way of thinking about
things.

It still seems that you\'re immune to that.

> Try asking anyone driving or better yet, selling electric cars and see if they know anything about Newtons.

And yet they should, because newtons are a direct measure of drag and
other inefficiencies.

> Not for me. $0/kWh is zero no matter the scale factor.

It\'s nice to know that Tesla\'s investors are paying your bills.

But entirely irrelevant.

CH

 

[Jasen Betts]

On 2020-07-22, Cydrome Leader <presence@MUNGEpanix.com> wrote:

Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:
On Tuesday, July 21, 2020 at 3:47:40 AM UTC-4, Clifford Heath wrote:
On 20/7/20 8:00 pm, Piotr Wyderski wrote:
Ricketty C wrote:

I thought the point of SI was to unify the use of units so everyone
could speak the same language?

People cannot even agree what a ton is.

WTF?!?? Why have multiple units like this?

Do you express fuel consumption of cars in square meters, as it should
have always been? This is the cross-section area of the virtual stream
of fuel running along your car when you are driving. Self-normalised,
doesn\'t need any \"per 100km\".

It\'s the cross-section area of a long thread of fuel that you car can
use to follow without losing speed. Ours does better than 0.1mm^2 only
on the highway, approximately a 0.25mm diameter thread of fuel. That
doesn\'t seem like much.

For electric cars, the measure is newtons, the force required to
maintain velocity against drag. Even for gasoline cars, that would be
more instructive, with a separate efficiency measure for the engine.

Clifford Heath.

Newton is not useful since it will vary hugely over speed and only be useful to compare cars directly while saying nothing about what you really care about, cost.

What really matters is $/mile or ???/mile, etc. Since the cost of electricity varies widely the energy per mile is useful as joules/mile or more commonly, even if not SI, kWh/mi. Of course these numbers will be related to driving patterns, but not the huge, direct impact that newtons suffer, just the same smaller effect we are used to with MPG.

A measure that would be similar to your newton number would simply be kW. This will relate more to useful units that can be used to find energy consumption and cost. I love mashing the accelerator and watching the kW meter run up to 400 in my car.

Oh yeah, my car needs 1.25 amps at 240 V to run on the highway at 60 MPH (97 kph) which will require a wire of about 20 gauge which is about 0.5 mm^2 cross section, 0.8 mm diameter.

What\'s the unit for heat rejection as in aircondition outside the US? We
use BTUs and Tons. Never seen a conversion chart or found a spec sheet for
aircoditioners not meant for the north american market.

Kilowatts.

eg: https://www.harveynorman.co.nz/event/triple-airpoints/kelvinator-split-cycle-air-conditioner-heat-pump-en-2.html

--
Jasen.

 

[Mike Coon]

In article <fb08d919-9189-4ef8-80f1-8583f7bae69do@googlegroups.com>,
whit3rd@gmail.com says...

I\'ve been experimenting (in the era of days-between-shaves and hiding behind a mask)
with shaving products. There\'s a goo called \'brushless shave cream\' that works well
in a shower, because you can flush your face with water and use a washcloth to
get it all off.

The proper quantity of the slime to use for a shave is between two garden slugs, and
one-quarter banana slug.

That matches the assumption that toothpaste is intended to be squeezed
out for the length of the bristled part of the brush. Thus if the tube
has a wide mouth everyone will use more toothpaste and thus buy more...

 

[Lasse Langwadt Christensen]

onsdag den 22. juli 2020 kl. 09.16.19 UTC+2 skrev Mikko OH2HVJ:

Cydrome Leader <presence@MUNGEpanix.com> writes:

What\'s the unit for heat rejection as in aircondition outside the US? We
use BTUs and Tons. Never seen a conversion chart or found a spec sheet for
aircoditioners not meant for the north american market.

The same as for most other energy flows - kW.

that would make sense, but I see many rated in btu/h
I\'m guessing because they come from the same factory making
them for the US market

 

[Lasse Langwadt Christensen]

onsdag den 22. juli 2020 kl. 09.16.19 UTC+2 skrev Mikko OH2HVJ:

Cydrome Leader <presence@MUNGEpanix.com> writes:

What\'s the unit for heat rejection as in aircondition outside the US? We
use BTUs and Tons. Never seen a conversion chart or found a spec sheet for
aircoditioners not meant for the north american market.

The same as for most other energy flows - kW.

that would make sense, but I see many rated in btu/h
I\'m guessing because they come from the same factory making
them for the US market

 

[Ricketty C]

On Wednesday, July 22, 2020 at 3:40:28 AM UTC-4, Mike Coon wrote:

In article <a784766d-74a6-4d21-a118-aa0006c8b6bao@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

You are thinking like some sort of scientist or engineer. Lord, no
one cares about Newtons! They care about Wh/mi which is exactly what
you wrote above. Wh into the battery, miles out, Wh/mi.

Strangely, lifejacket buoyancy is specified in newtons. Sometimes they
even have dinky batteries...

I found that out when trying to buy a less expensive PFD on the Asian channels. They don\'t bother with any US approvals and often don\'t even specify the buoyancy. But that make sense. Submerge a PFD and it will provide a force pushing to the surface.

I never did find a PFD that is actually adequate for me. I\'m on the large side and when you do the math, the US adult size is not really adequate, barely keeping my head above the surface. My mouth is just an inch or so out of the water. The Chinese PFDs have even less buoyancy for the most part, but then their size tends to be less, so that makes some sense. Like many things, they don\'t address a foreign market.

--

Rick C.

-++ Get 1,000 miles of free Supercharging
-++ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Wednesday, July 22, 2020 at 3:40:28 AM UTC-4, Mike Coon wrote:

In article <a784766d-74a6-4d21-a118-aa0006c8b6bao@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

You are thinking like some sort of scientist or engineer. Lord, no
one cares about Newtons! They care about Wh/mi which is exactly what
you wrote above. Wh into the battery, miles out, Wh/mi.

Strangely, lifejacket buoyancy is specified in newtons. Sometimes they
even have dinky batteries...

I found that out when trying to buy a less expensive PFD on the Asian channels. They don\'t bother with any US approvals and often don\'t even specify the buoyancy. But that make sense. Submerge a PFD and it will provide a force pushing to the surface.

I never did find a PFD that is actually adequate for me. I\'m on the large side and when you do the math, the US adult size is not really adequate, barely keeping my head above the surface. My mouth is just an inch or so out of the water. The Chinese PFDs have even less buoyancy for the most part, but then their size tends to be less, so that makes some sense. Like many things, they don\'t address a foreign market.

--

Rick C.

-++ Get 1,000 miles of free Supercharging
-++ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Wednesday, July 22, 2020 at 3:40:28 AM UTC-4, Mike Coon wrote:

In article <a784766d-74a6-4d21-a118-aa0006c8b6bao@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

You are thinking like some sort of scientist or engineer. Lord, no
one cares about Newtons! They care about Wh/mi which is exactly what
you wrote above. Wh into the battery, miles out, Wh/mi.

Strangely, lifejacket buoyancy is specified in newtons. Sometimes they
even have dinky batteries...

I found that out when trying to buy a less expensive PFD on the Asian channels. They don\'t bother with any US approvals and often don\'t even specify the buoyancy. But that make sense. Submerge a PFD and it will provide a force pushing to the surface.

I never did find a PFD that is actually adequate for me. I\'m on the large side and when you do the math, the US adult size is not really adequate, barely keeping my head above the surface. My mouth is just an inch or so out of the water. The Chinese PFDs have even less buoyancy for the most part, but then their size tends to be less, so that makes some sense. Like many things, they don\'t address a foreign market.

--

Rick C.

-++ Get 1,000 miles of free Supercharging
-++ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Wednesday, July 22, 2020 at 7:25:20 AM UTC-4, Clifford Heath wrote:

On 22/7/20 11:33 am, Ricketty C wrote:
On Tuesday, July 21, 2020 at 8:16:30 PM UTC-4, Clifford Heath wrote:
On 22/7/20 5:28 am, Ricketty C wrote:
On Tuesday, July 21, 2020 at 11:52:51 AM UTC-4, Lasse Langwadt Christensen wrote:
tirsdag den 21. juli 2020 kl. 17.18.42 UTC+2 skrev Ricketty C:
On Tuesday, July 21, 2020 at 3:47:40 AM UTC-4, Clifford Heath wrote:
For electric cars, the measure is newtons, the force required to
maintain velocity against drag.
Newton is not useful since it will vary...

More prevarication snipped...

But that\'s not what people actually use. You put kWH into your battery,
you get km out. The ratio of those is in newtons.

You are thinking like some sort of scientist or engineer. Lord, no one cares about Newtons! They care about Wh/mi

No, it\'s miles that no-one cares about. Civilised countries barely even
remember those.

The point of my entry into this thread wasn\'t to remind people what they
already care about. It was to suggest a different way of thinking about
things.

It still seems that you\'re immune to that.

I can differentiate a good idea from a bad one. The idea of inventing a new standard index to compare items is not a new thought. That\'s why I mentioned MPGe. Using newtons adds nothing to the measurement and moves further away from what people care about, fuel consumption. You might as well try to promote drag coefficient.

Try asking anyone driving or better yet, selling electric cars and see if they know anything about Newtons.

And yet they should, because newtons are a direct measure of drag and
other inefficiencies.

You still aren\'t getting it. You are thinking like an engineer. You have totally failed to explain in terms a layman would understand why using newtons is better than using Wh/mi. That\'s one of the reasons why the Challenger disaster ended the way it did. The engineers were largely unable to explain their thinking, saying a launch was “away from goodness in the current database”.

Using newtons as a metric of EV efficiency would produce similar results in the car buying public. Why can\'t you see that???

Not for me. $0/kWh is zero no matter the scale factor.

It\'s nice to know that Tesla\'s investors are paying your bills.

You seem to fail to understand economics and contract law. A promotion was offered to sell cars many of which would not have been sold without. This helped to ensure the survival of the company. Don\'t talk about anyone paying my bills. I paid an awful lot of Tesla bills with my purchase, now they are simply honoring their contract.

--

Rick C.

+-- Get 1,000 miles of free Supercharging
+-- Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Wednesday, July 22, 2020 at 7:25:20 AM UTC-4, Clifford Heath wrote:

On 22/7/20 11:33 am, Ricketty C wrote:
On Tuesday, July 21, 2020 at 8:16:30 PM UTC-4, Clifford Heath wrote:
On 22/7/20 5:28 am, Ricketty C wrote:
On Tuesday, July 21, 2020 at 11:52:51 AM UTC-4, Lasse Langwadt Christensen wrote:
tirsdag den 21. juli 2020 kl. 17.18.42 UTC+2 skrev Ricketty C:
On Tuesday, July 21, 2020 at 3:47:40 AM UTC-4, Clifford Heath wrote:
For electric cars, the measure is newtons, the force required to
maintain velocity against drag.
Newton is not useful since it will vary...

More prevarication snipped...

But that\'s not what people actually use. You put kWH into your battery,
you get km out. The ratio of those is in newtons.

You are thinking like some sort of scientist or engineer. Lord, no one cares about Newtons! They care about Wh/mi

No, it\'s miles that no-one cares about. Civilised countries barely even
remember those.

The point of my entry into this thread wasn\'t to remind people what they
already care about. It was to suggest a different way of thinking about
things.

It still seems that you\'re immune to that.

I can differentiate a good idea from a bad one. The idea of inventing a new standard index to compare items is not a new thought. That\'s why I mentioned MPGe. Using newtons adds nothing to the measurement and moves further away from what people care about, fuel consumption. You might as well try to promote drag coefficient.

Try asking anyone driving or better yet, selling electric cars and see if they know anything about Newtons.

And yet they should, because newtons are a direct measure of drag and
other inefficiencies.

You still aren\'t getting it. You are thinking like an engineer. You have totally failed to explain in terms a layman would understand why using newtons is better than using Wh/mi. That\'s one of the reasons why the Challenger disaster ended the way it did. The engineers were largely unable to explain their thinking, saying a launch was “away from goodness in the current database”.

Using newtons as a metric of EV efficiency would produce similar results in the car buying public. Why can\'t you see that???

Not for me. $0/kWh is zero no matter the scale factor.

It\'s nice to know that Tesla\'s investors are paying your bills.

You seem to fail to understand economics and contract law. A promotion was offered to sell cars many of which would not have been sold without. This helped to ensure the survival of the company. Don\'t talk about anyone paying my bills. I paid an awful lot of Tesla bills with my purchase, now they are simply honoring their contract.

--

Rick C.

+-- Get 1,000 miles of free Supercharging
+-- Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Wednesday, July 22, 2020 at 7:25:20 AM UTC-4, Clifford Heath wrote:

On 22/7/20 11:33 am, Ricketty C wrote:
On Tuesday, July 21, 2020 at 8:16:30 PM UTC-4, Clifford Heath wrote:
On 22/7/20 5:28 am, Ricketty C wrote:
On Tuesday, July 21, 2020 at 11:52:51 AM UTC-4, Lasse Langwadt Christensen wrote:
tirsdag den 21. juli 2020 kl. 17.18.42 UTC+2 skrev Ricketty C:
On Tuesday, July 21, 2020 at 3:47:40 AM UTC-4, Clifford Heath wrote:
For electric cars, the measure is newtons, the force required to
maintain velocity against drag.
Newton is not useful since it will vary...

More prevarication snipped...

But that\'s not what people actually use. You put kWH into your battery,
you get km out. The ratio of those is in newtons.

You are thinking like some sort of scientist or engineer. Lord, no one cares about Newtons! They care about Wh/mi

No, it\'s miles that no-one cares about. Civilised countries barely even
remember those.

The point of my entry into this thread wasn\'t to remind people what they
already care about. It was to suggest a different way of thinking about
things.

It still seems that you\'re immune to that.

I can differentiate a good idea from a bad one. The idea of inventing a new standard index to compare items is not a new thought. That\'s why I mentioned MPGe. Using newtons adds nothing to the measurement and moves further away from what people care about, fuel consumption. You might as well try to promote drag coefficient.

Try asking anyone driving or better yet, selling electric cars and see if they know anything about Newtons.

And yet they should, because newtons are a direct measure of drag and
other inefficiencies.

You still aren\'t getting it. You are thinking like an engineer. You have totally failed to explain in terms a layman would understand why using newtons is better than using Wh/mi. That\'s one of the reasons why the Challenger disaster ended the way it did. The engineers were largely unable to explain their thinking, saying a launch was “away from goodness in the current database”.

Using newtons as a metric of EV efficiency would produce similar results in the car buying public. Why can\'t you see that???

Not for me. $0/kWh is zero no matter the scale factor.

It\'s nice to know that Tesla\'s investors are paying your bills.

You seem to fail to understand economics and contract law. A promotion was offered to sell cars many of which would not have been sold without. This helped to ensure the survival of the company. Don\'t talk about anyone paying my bills. I paid an awful lot of Tesla bills with my purchase, now they are simply honoring their contract.

--

Rick C.

+-- Get 1,000 miles of free Supercharging
+-- Tesla referral code - https://ts.la/richard11209

 

[John S]

On 7/20/2020 1:23 AM, Ricketty C wrote:

I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates.

Pascals
mmH2O
cmH2O
mBar
and another one I didn\'t even recognize. lol

Likewise I\'m finding flow rates indicated as either
ml/s
SLM (standard liters per minute)

WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units.

Damn them to hell!!!

Just to piss you off. It worked!!!

 

[John S]

On 7/20/2020 1:23 AM, Ricketty C wrote:

I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates.

Pascals
mmH2O
cmH2O
mBar
and another one I didn\'t even recognize. lol

Likewise I\'m finding flow rates indicated as either
ml/s
SLM (standard liters per minute)

WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units.

Damn them to hell!!!

Just to piss you off. It worked!!!

 

[John S]

On 7/20/2020 1:23 AM, Ricketty C wrote:

I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates.

Pascals
mmH2O
cmH2O
mBar
and another one I didn\'t even recognize. lol

Likewise I\'m finding flow rates indicated as either
ml/s
SLM (standard liters per minute)

WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units.

Damn them to hell!!!

Just to piss you off. It worked!!!

 

[Cydrome Leader]

omnilobe@gmail.com wrote:

On Monday, July 20, 2020 at 5:01:30 PM UTC-10, Ricketty C wrote:
On Monday, July 20, 2020 at 6:11:07 PM UTC-4, omni...@gmail.com wrote:
On Monday, July 20, 2020 at 11:41:38 AM UTC-10, DemonicTubes wrote:
On Monday, July 20, 2020 at 12:23:22 AM UTC-6, Ricketty C wrote:
I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates.

Pascals
mmH2O
cmH2O
mBar
and another one I didn\'t even recognize. lol

Likewise I\'m finding flow rates indicated as either
ml/s
SLM (standard liters per minute)

WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units.

Damn them to hell!!!

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Torque units are equally frustrating. According to SI it is supposed to be Nm. I am always converting Nm, Ncm, ft-lb, in-lb., oz-in., etc.

We are also a chemistry lab. Concentration units...grrr! This is worse. Units can be mass-per-volume or number-per-volume. Depending on the industry we are serving, the preferred units are different. It gets a bit obnoxious constantly converting mg/mL to nanomolar (for instance). Since our software analysis needs everything in molarity, I am often scrambling to find the molecular weight of this that and the other thing. And that is just the metric units!

Always makes me chuckle when somebody says Americans don\'t understand metric. We understand metric just fine, we just also happen to know a bunch of other units and know how to convert between them.

One atmosphere of pressure is 101,325 Pascals metric.

Torque is in units of Joules

So does a torque of 1 Nm do 1 joule of work in a radian of rotation?


The Ohm is events per second.

Got me on that one. How does that work?

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

A torque wrench rotates a bolt to store energy
in the spring steel threads. A force of one Newton
with a wrench 1 meter long will store 1 Joule of
energy and heat in the bolt. The bending of the threads
is like a spring storing energy.

Nonsense. Torque measurements are not the same as a force applied over a
distance.

It doesn\'t take, or produce 1 horsepower to hang 550 pounds off a bar 1
foot long for 1 second.

 

[John S]

On 7/25/2020 6:41 PM, Cydrome Leader wrote:

omnilobe@gmail.com wrote:
On Monday, July 20, 2020 at 5:01:30 PM UTC-10, Ricketty C wrote:
On Monday, July 20, 2020 at 6:11:07 PM UTC-4, omni...@gmail.com wrote:
On Monday, July 20, 2020 at 11:41:38 AM UTC-10, DemonicTubes wrote:
On Monday, July 20, 2020 at 12:23:22 AM UTC-6, Ricketty C wrote:
I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates.

Pascals
mmH2O
cmH2O
mBar
and another one I didn\'t even recognize. lol

Likewise I\'m finding flow rates indicated as either
ml/s
SLM (standard liters per minute)

WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units.

Damn them to hell!!!

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Torque units are equally frustrating. According to SI it is supposed to be Nm. I am always converting Nm, Ncm, ft-lb, in-lb., oz-in., etc.

We are also a chemistry lab. Concentration units...grrr! This is worse. Units can be mass-per-volume or number-per-volume. Depending on the industry we are serving, the preferred units are different. It gets a bit obnoxious constantly converting mg/mL to nanomolar (for instance). Since our software analysis needs everything in molarity, I am often scrambling to find the molecular weight of this that and the other thing. And that is just the metric units!

Always makes me chuckle when somebody says Americans don\'t understand metric. We understand metric just fine, we just also happen to know a bunch of other units and know how to convert between them.

One atmosphere of pressure is 101,325 Pascals metric.

Torque is in units of Joules

So does a torque of 1 Nm do 1 joule of work in a radian of rotation?


The Ohm is events per second.

Got me on that one. How does that work?

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

A torque wrench rotates a bolt to store energy
in the spring steel threads. A force of one Newton
with a wrench 1 meter long will store 1 Joule of
energy and heat in the bolt. The bending of the threads
is like a spring storing energy.

Nonsense. Torque measurements are not the same as a force applied over a
distance.

Please explain torque measurements. An inquiring mind needs to know.

It doesn\'t take, or produce 1 horsepower to hang 550 pounds off a bar 1
foot long for 1 second.

Even if the 550lb is attached perpendicular to the axis of the bar and
displaced from the center of the bar by 1 foot? Why not? I think it is
called 1 ft*lbf of torque.

https://en.wikipedia.org/wiki/Torque

 

[server]

On Tue, 21 Jul 2020 00:00:25 -0700 (PDT), omnilobe@gmail.com wrote:

On Monday, July 20, 2020 at 5:01:30 PM UTC-10, Ricketty C wrote:
On Monday, July 20, 2020 at 6:11:07 PM UTC-4, omni...@gmail.com wrote:
On Monday, July 20, 2020 at 11:41:38 AM UTC-10, DemonicTubes wrote:
On Monday, July 20, 2020 at 12:23:22 AM UTC-6, Ricketty C wrote:
I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates.

Pascals
mmH2O
cmH2O
mBar
and another one I didn\'t even recognize. lol

Likewise I\'m finding flow rates indicated as either
ml/s
SLM (standard liters per minute)

WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units.

Damn them to hell!!!

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Torque units are equally frustrating. According to SI it is supposed to be Nm. I am always converting Nm, Ncm, ft-lb, in-lb., oz-in., etc.

We are also a chemistry lab. Concentration units...grrr! This is worse. Units can be mass-per-volume or number-per-volume. Depending on the industry we are serving, the preferred units are different. It gets a bit obnoxious constantly converting mg/mL to nanomolar (for instance). Since our software analysis needs everything in molarity, I am often scrambling to find the molecular weight of this that and the other thing. And that is just the metric units!

Always makes me chuckle when somebody says Americans don\'t understand metric. We understand metric just fine, we just also happen to know a bunch of other units and know how to convert between them.

One atmosphere of pressure is 101,325 Pascals metric.

Torque is in units of Joules

So does a torque of 1 Nm do 1 joule of work in a radian of rotation?


The Ohm is events per second.

Got me on that one. How does that work?

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

A torque wrench rotates a bolt to store energy
in the spring steel threads. A force of one Newton
with a wrench 1 meter long will store 1 Joule of
energy and heat in the bolt. The bending of the threads
is like a spring storing energy.

The work done to tighten a bolt goes mostly into heat. It\'s not
recoverable. It takes *more* work to un-do a bolt. That\'s why nuts
don\'t spontaneously fly off bolts.

Torque is measured in units of force*distance. So is energy. But a
newton-meter of torque is not a joule. Torque is neither power nor
energy, it\'s just force.

You can hang a big weight on the end a long torque wrench for a
hundred years, and nothing happens.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Ricketty C]

On Saturday, July 25, 2020 at 7:41:58 PM UTC-4, Cydrome Leader wrote:

omnilobe@gmail.com wrote:
On Monday, July 20, 2020 at 5:01:30 PM UTC-10, Ricketty C wrote:
On Monday, July 20, 2020 at 6:11:07 PM UTC-4, omni...@gmail.com wrote:
On Monday, July 20, 2020 at 11:41:38 AM UTC-10, DemonicTubes wrote:
On Monday, July 20, 2020 at 12:23:22 AM UTC-6, Ricketty C wrote:
I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates.

Pascals
mmH2O
cmH2O
mBar
and another one I didn\'t even recognize. lol

Likewise I\'m finding flow rates indicated as either
ml/s
SLM (standard liters per minute)

WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units.

Damn them to hell!!!

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Torque units are equally frustrating. According to SI it is supposed to be Nm. I am always converting Nm, Ncm, ft-lb, in-lb., oz-in., etc.

We are also a chemistry lab. Concentration units...grrr! This is worse. Units can be mass-per-volume or number-per-volume. Depending on the industry we are serving, the preferred units are different. It gets a bit obnoxious constantly converting mg/mL to nanomolar (for instance). Since our software analysis needs everything in molarity, I am often scrambling to find the molecular weight of this that and the other thing. And that is just the metric units!

Always makes me chuckle when somebody says Americans don\'t understand metric. We understand metric just fine, we just also happen to know a bunch of other units and know how to convert between them.

One atmosphere of pressure is 101,325 Pascals metric.

Torque is in units of Joules

So does a torque of 1 Nm do 1 joule of work in a radian of rotation?


The Ohm is events per second.

Got me on that one. How does that work?

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

A torque wrench rotates a bolt to store energy
in the spring steel threads. A force of one Newton
with a wrench 1 meter long will store 1 Joule of
energy and heat in the bolt. The bending of the threads
is like a spring storing energy.

Nonsense. Torque measurements are not the same as a force applied over a
distance.

It doesn\'t take, or produce 1 horsepower to hang 550 pounds off a bar 1
foot long for 1 second.

The measurement of torque is not the same as a measurement of energy, but the units are the same... because if you rotate 1 radian against a torque of n Nm you will do n Nm of work. The 1 radian is dimensionless.

It only takes a moment to understand this if you consider the definition of a radian.

--

Rick C.

+-+ Get 1,000 miles of free Supercharging
+-+ Tesla referral code - https://ts.la/richard11209

 

[Lasse Langwadt Christensen]

søndag den 26. juli 2020 kl. 02.03.12 UTC+2 skrev John S:

On 7/25/2020 6:41 PM, Cydrome Leader wrote:
omnilobe@gmail.com wrote:
On Monday, July 20, 2020 at 5:01:30 PM UTC-10, Ricketty C wrote:
On Monday, July 20, 2020 at 6:11:07 PM UTC-4, omni...@gmail.com wrote:
On Monday, July 20, 2020 at 11:41:38 AM UTC-10, DemonicTubes wrote:
On Monday, July 20, 2020 at 12:23:22 AM UTC-6, Ricketty C wrote:
I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates.

Pascals
mmH2O
cmH2O
mBar
and another one I didn\'t even recognize. lol

Likewise I\'m finding flow rates indicated as either
ml/s
SLM (standard liters per minute)

WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units.

Damn them to hell!!!

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

Torque units are equally frustrating. According to SI it is supposed to be Nm. I am always converting Nm, Ncm, ft-lb, in-lb., oz-in., etc.

We are also a chemistry lab. Concentration units...grrr! This is worse. Units can be mass-per-volume or number-per-volume. Depending on the industry we are serving, the preferred units are different. It gets a bit obnoxious constantly converting mg/mL to nanomolar (for instance). Since our software analysis needs everything in molarity, I am often scrambling to find the molecular weight of this that and the other thing. And that is just the metric units!

Always makes me chuckle when somebody says Americans don\'t understand metric. We understand metric just fine, we just also happen to know a bunch of other units and know how to convert between them.

One atmosphere of pressure is 101,325 Pascals metric.

Torque is in units of Joules

So does a torque of 1 Nm do 1 joule of work in a radian of rotation?


The Ohm is events per second.

Got me on that one. How does that work?

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

A torque wrench rotates a bolt to store energy
in the spring steel threads. A force of one Newton
with a wrench 1 meter long will store 1 Joule of
energy and heat in the bolt. The bending of the threads
is like a spring storing energy.

Nonsense. Torque measurements are not the same as a force applied over a
distance.

Please explain torque measurements. An inquiring mind needs to know.


It doesn\'t take, or produce 1 horsepower to hang 550 pounds off a bar 1
foot long for 1 second.


Even if the 550lb is attached perpendicular to the axis of the bar and
displaced from the center of the bar by 1 foot? Why not? I think it is
called 1 ft*lbf of torque.

https://en.wikipedia.org/wiki/Torque

wrap a rope around a cylinder with 1 meter radius, pull on that rope with
the force of 1 Newton, that is 1Nm of torque, pull on the rope with 1 Newton until you have unwound 1 meter of rope and you have done 1 joule of work

both are 1 newton and 1 meter but there is a difference

 

[whit3rd]

On Saturday, July 25, 2020 at 6:33:11 PM UTC-7, Ricketty C wrote:

The measurement of torque is not the same as a measurement of energy, but the units are the same... because if you rotate 1 radian against a torque of n Nm you will do n Nm of work. The 1 radian is dimensionless.

Yes, the distinction between work (force applied dot-product to displacement) and
torque (force applied circumferentially on a lever arm radial from the center)
means that torque can happen with zero work. But, the units are the same
(and scaling torque to another units system doesn\'t require the
dot-product selectivity of the force and displacement directions).