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Old 15-10-2015, 13:12   #286
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Re: Convenience of the metric system

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Originally Posted by avb3 View Post
In Canadian grocery stores (who have been metric for 3 decades) to this day, you will see large pricing in pounds or ounces, and in small, the price per Kilogram or per 100 grams. The only legal way to sell is metric, and that is what the grocery till will ring up, but even those that took only metric in school visualize in pounds.

There were a number of years when we first went metric where it was illegal to show the prices in imperial, but the backlash was so strong that the regulations were changed.

Here is an example for a flyer...notice the price/lb is large, price/kg is small.
I have heard of being resistant to change but 3 decades, thats not resistance -thats commitment. Eh.
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Old 15-10-2015, 13:23   #287
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Re: Convenience of the metric system

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Originally Posted by Lars_L View Post
Force is gravity multiplyed with weight.

In the metric system is
Gravity 9.81 m/s
Weight is measured in kg.
Force is measured in N, and this will give N = 9.81 m/s * kg.

In the imperial system that would be:
Gravity 32 2 /s.
Weight is measured in pound. I call it pound(w).
Force is measured in pound. I call it pound(f).

This will give that pound(f) = 32 2 /s * pound(w).

I know that the imperial system is crazy but I hope that I have misunderstood something.
Maybe I can clarify a little for you, starting with the terminology. Maybe a translation issue since I see you're from Sweden. Congratulations on doing this in English as I wouldn't even know how to say hello in Swedish.

To avoid confusion, what you are calling weight is correctly referred to as mass. This property is independent of gravity (which is a force) so will be the same one the Earth, moon or in outer space.

In metric mass is in Kg, in English it is in Slugs (a unit that no one has ever heard of or uses except in engineering or a college physics class). Weight is mass related to force (which again could be gravity). So something that weighs 66 lbs on the Earth would weigh 11 lbs on the moon but the mass in slugs would be the same.

In metric the equivalent to weight in pounds would be a Newton which is defined as 1 kgm/s2
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Old 15-10-2015, 15:42   #288
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Re: Convenience of the metric system

I haven't been keeping up with this thread, so not sure where you are going with this, but you have some errors in what you are saying.
And it might be a bit lost in translation (perhaps you are calling mass "weight", but at least in US, we consider weight as the force of gravity on a certain mass), but science has to be exactly right!
In the metric system, kg is a unit of mass. Force, as you say, is measured in newtons.
In the imperial system, the unit of mass is the slug. Force is measured in pounds.

Gravity is about 32.174 ft/sec squared


Quote:
Originally Posted by Lars_L View Post
Force is gravity multiplyed with weight.

In the metric system is
Gravity 9.81 m/s
Weight is measured in kg.
Force is measured in N, and this will give N = 9.81 m/s * kg.

In the imperial system that would be:
Gravity 32 2 /s.
Weight is measured in pound. I call it pound(w).
Force is measured in pound. I call it pound(f).

This will give that pound(f) = 32 2 /s * pound(w).

I know that the imperial system is crazy but I hope that I have misunderstood something.
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Old 15-10-2015, 16:15   #289
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Re: Convenience of the metric system

Even in Europe an item with mass of 1kg weighs approx 9.81N on earth and the same item weighs approx 1.63N on the moon. Mass doesn't change, weight is a force so changes with gravity.

However in normal conversation if I ask my wife how heavy she is she tells me, firstly to mind my own business and secondly that she weighs 60kgs, the word mass is not used!

As a 55 year old Brit I did all my school and university studies in metric units but if I look at an object, I still think in inches feet or pounds, but if I measure it I would use a tape measure in cm and scales in kgs, strange!

I believe there is research, ongoing, about a new non dimensional ( non dimensional as you have no idea how large it might be) metric/si unit , it is directly proportional to the square of a yachts propellor diameter, in inches x the sail area, in meters, and is commonly referred to as the boat buck.

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Old 15-10-2015, 16:16   #290
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Re: Convenience of the metric system

Quote:
Originally Posted by Lars_L View Post
Force is gravity multiplyed with weight.

In the metric system is
Gravity 9.81 m/s
Weight is measured in kg.
Force is measured in N, and this will give N = 9.81 m/s * kg.

In the imperial system that would be:
(1)Gravity 32’ 2 ” /s.
(2)Weight is measured in pound. I call it pound(w).
Force is measured in pound. I call it pound(f).

(3) This will give that pound(f) = 32’ 2 ” /s * pound(w).

I know that the imperial system is crazy but I hope that I have misunderstood something.
A few points:

1. Gravity = 32’ 2 9/100" /s.

2. It is more correct to say:
Mass is measured in pounds(mass) or lb(m)
Weight (or any other force) is measures in pounds(force) or lb(f)

3. Just because you are using imperial units, there is no requirement to drop metric arithmetic. It is quite permissible, and indeed very sensible, to use 32.17 ft/s.

4. Another way to write that would be 1 lb(f) = 32.17 lb(m)ft/sec at the earth's surface.

In layman terms however, a pound(f) and a pound(m) define the same amount of "stuff" at the earth's surface.

This is a good illustration of why technical people working in mixed dimensional imperial units use the slug rather than the lb(mass).
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Old 15-10-2015, 17:31   #291
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Re: Convenience of the metric system

Are we still talking 'appendixes' here

Sorry, 'appendexes'
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Old 15-10-2015, 19:09   #292
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Re: Convenience of the metric system

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Originally Posted by Rustic Charm View Post
Are we still talking 'appendixes' here

Sorry, 'appendexes'
You were right first time.
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Old 15-10-2015, 21:20   #293
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Re: Convenience of the metric system

Quote:
Originally Posted by Lars_L View Post
Force is gravity multiplyed with weight.

In the metric system is
Gravity 9.81 m/s
Weight is measured in kg.
Force is measured in N, and this will give N = 9.81 m/s * kg.

In the imperial system that would be:
Gravity 32 2 /s.
Weight is measured in pound. I call it pound(w).
Force is measured in pound. I call it pound(f).

This will give that pound(f) = 32 2 /s * pound(w).

I know that the imperial system is crazy but I hope that I have misunderstood something.
Actually:

Acceleration due to gravity is 9.8067 m/s or 32.174 ft/s

Mass is measured in kilograms (or various permutations) or slugs (though colloquially non-technical folks will use pounds).

Force is measured in Newtons (though colloquially non-technical folks will use kilograms) or pounds.

Force is Acceleration time Mass

Weight is the force experienced by a mass resisting gravity specifically.

In common usage if you ask someone what they weigh in Europe they will answer using units of kilograms which is technically incorrect since they should be answering in unit of Newtons. In the US they will answer in units of pounds which is technically correct as pound is technically defined as a unit of force.

In both places if you ask someone what they mass, most people will look at you funny and ask if you mean what they weigh. In colloquial usage mass and weight are equivalent whether you are using Imperial/SAE or SI/metric.

If you want to argue for the superiority of SI, I agree for various reasons, but distinctions about mass and weight would not be one of them.
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Old 15-10-2015, 22:15   #294
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Re: Convenience of the metric system

I recall well the day Canada went metric. There was much fanfare that the North American continent was going to join hands and jump into the metric system together. I was living in Vancouver, BC at the time and was really interested to see how service stations were going to handle the switch from gallons to liters. There were special stickers issued to put on stock that retail outlets had to change from pints and gallons to liters and special instructions to recalibrate fuel pumps. Even car manufacturers who had plenty of warning began installing speedometers that included both mph and kph because many of the US vehicles were made in Windsor, Ontario.
On the agreed upon date, Canada lept off the metric bridge but 1/2 hour before launch some American political dickhead got cold feet and refused to go along with the agreement. Since then, Canada has never trusted what an American politician had agreed to and America continues to be the laughing stock of world commerce. So endith the history lesson... Cheers, Phil
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Old 16-10-2015, 09:45   #295
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Re: Convenience of the metric system

It's good to hear that, in countries that have forced the metric system on the population, people still think in imperial units.

I believe that's because that the imperial system just makes more intuitive sense.

The decimal system is an artificial construct, which came about solely through the accident of humans having ten fingers. It's not particularly useful otherwise, since 10 is only divisible by 2 and 5.

The binary system would be a more natural way to count.

That's what we do in the imperial system: Two tablespoons are an ounce. Eight (2x2x2) ounces are a cup. Two cups are a pint. Two pints are a quart. Or we can go straight to four (2x2) cups in a quart. Four quarts in a gallon. Or, just to make the math simple, 128 (2x2x2x2x2x2x2) ounces in a gallon. 128 is divisible by 2, 4, 8, 16, 32, and 64. Note that a "half gallon" (2x2x2x2x2x2 ounces) is a common measurement used in the imperial system.

Or put another way, you can divide a gallon in half, in half again, and in half again, and again, and again, and again, and again, and again. With each half, you get a common unit in the imperial system.

Now look at money. A US dollar, our basic unit, is 100 cents. Just like the metric system. One fourth of that, a "quarter", is a common concept that even young children easily grasp. Dimes and nickles are available, but that takes a little more thought. Interestingly, we don't really have a way to divide dollars into eighths, and it makes things confusing.

But that's a recent problem. The term "two bits" is a leftover phrase from the colonial period, when the Spanish dollar was used. The Spanish dollar was called a "piece of eight", which was equal to 8 Spanish reales. One eighth of a dollar or one silver real was one "bit", which is equal to 12.5 cents. Nobody called it "12.5 cents". They called it one bit. Another vote against the metric system. By the way, the word "bit" lives on in the computer world, where it's one-eighth of a "byte."

To this day, we can easily understand the concept of "two bits", or one-eight of a dollar, even though we don't have a "bit" coin any more. We have "bitcoin" now, but that's a whole different discussion.

So, my conclusion is that it's natural to think in multiples of 2, also known as the binary system. Decimal, aka Metric, is an artificial construct that's nowhere near as useful or easy to understand as its proponents suggest.
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Old 16-10-2015, 10:08   #296
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Re: Convenience of the metric system

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Originally Posted by CaptTom View Post
It's good to hear that, in countries that have forced the metric system on the population, people still think in imperial units.

I believe that's because that the imperial system just makes more intuitive sense.

The decimal system is an artificial construct, which came about solely through the accident of humans having ten fingers. It's not particularly useful otherwise, since 10 is only divisible by 2 and 5.

The binary system would be a more natural way to count.

That's what we do in the imperial system: Two tablespoons are an ounce. Eight (2x2x2) ounces are a cup. Two cups are a pint. Two pints are a quart. Or we can go straight to four (2x2) cups in a quart. Four quarts in a gallon. Or, just to make the math simple, 128 (2x2x2x2x2x2x2) ounces in a gallon. 128 is divisible by 2, 4, 8, 16, 32, and 64. Note that a "half gallon" (2x2x2x2x2x2 ounces) is a common measurement used in the imperial system.

Or put another way, you can divide a gallon in half, in half again, and in half again, and again, and again, and again, and again, and again. With each half, you get a common unit in the imperial system.

Now look at money. A US dollar, our basic unit, is 100 cents. Just like the metric system. One fourth of that, a "quarter", is a common concept that even young children easily grasp. Dimes and nickles are available, but that takes a little more thought. Interestingly, we don't really have a way to divide dollars into eighths, and it makes things confusing.

But that's a recent problem. The term "two bits" is a leftover phrase from the colonial period, when the Spanish dollar was used. The Spanish dollar was called a "piece of eight", which was equal to 8 Spanish reales. One eighth of a dollar or one silver real was one "bit", which is equal to 12.5 cents. Nobody called it "12.5 cents". They called it one bit. Another vote against the metric system. By the way, the word "bit" lives on in the computer world, where it's one-eighth of a "byte."

To this day, we can easily understand the concept of "two bits", or one-eight of a dollar, even though we don't have a "bit" coin any more. We have "bitcoin" now, but that's a whole different discussion.

So, my conclusion is that it's natural to think in multiples of 2, also known as the binary system. Decimal, aka Metric, is an artificial construct that's nowhere near as useful or easy to understand as its proponents suggest.
For small quantities, simpler calculations like a recipe for cooking something what you describe as a binary system can work.

However, naming smaller units of two might work for small sizes but requires memorizing a name for every order of magnitude. Once you get past cups, pints, quarts, gallons to larger and larger volumes that system will become totally unwieldy. If you go to true binary using just ones and zeros for all numbers that also become unwieldy with larger numbers.

In engineering I extensively used all three systems: metric, imperial and pure binary IE ones and zeros only. For anything complex I personally prefer metric by a large margin. Since metric to me is the most useful in large or complex calculations it just makes sense to use it for everything and not have to deal with two different systems.
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Old 16-10-2015, 10:45   #297
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Re: Convenience of the metric system

In the metric system in Sweden is:
Mass is the same as weight and measured in kg. Therefore we seldom use mass.

In the imperial system:
Weight is as force measured in pound (lb).

The gravity is usually only written with two decimals since it wary where on earth its measured. 9.81 m/s

If one person has a length of 63 and another have the length of 410, what is the average length?


The base of 2.
Length. For 1 inch they take the half, and the half and so on.
But in the other direction?
12 inch for a foot. Where do the base two come in that?
Next step. 3 foot on a yard. The base two?
And how many yard is there on a mile?
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Old 16-10-2015, 10:53   #298
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Re: Convenience of the metric system

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I recall well the day Canada went metric. ..............Since then, Canada has never trusted what an American politician had agreed to and America continues to be the laughing stock of world commerce.
What took 'em so long?
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Old 16-10-2015, 11:58   #299
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Re: Convenience of the metric system

Canada went metric?!


Astounding. How come their carpenters still buy plywood sheets in 4'x8' pieces, and they still use inches to measure before they cut?


I'm all for metric, but it needs a handy unit somewhere around one foot, or one cubit, in length, so there's a handy way to describe things without pesky decimals.


"Three decimeters" just doesn't do it. Even the French don't use decimeters.
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Old 16-10-2015, 12:15   #300
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Re: Convenience of the metric system

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Originally Posted by Adelie View Post



In common usage if you ask someone what they weigh in Europe they will answer using units of kilograms which is technically incorrect since they should be answering in unit of Newtons. In the US they will answer in units of pounds which is technically correct as pound is technically defined as a unit of force.


There are a few contexts where Newton is used however. I see load limits in warehouse floors indicated in N/m2. And there's life jackets.


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