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Thread: Units of measurement

  1. #21
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    Quote Originally Posted by MAC702 View Post
    The word metric is for measurement, not specifically length. I always assumed the meter comes from the metric system, not vice versa. Yes, it's the modern International System, or SI, also, but it's not wrong to call it the metric system. EVERYONE knows what it means.

    When we talk about the metrics of a baseball pitcher, or anything, we aren't referring to measurements of length usually.
    Definition of metric - relating to or based on the metre as a unit of length, relating to or denoting a metric.
    English Oxford Dictionary.
    Si hoc legere scis nimium eruditionis habes.

  2. #22
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    There are multiple issues here.

    SI is convenient because it is a self consistent system of units. When physics relates two properties, the units are related so that you don't need conversion factors or 'constants' to make the equations work out.

    In SI you can answer F=MA without having to somehow work in '32 feet per second per second' or other similar nonsense.

    But the objection to the _particular_ units selected remains, and the selection was in many ways political.

    Much of the 'forced metrification' uses units that are only vaguely related to SI...places switching from miles per hour to kilometers per hour as if this were meaningful. Pressure gauges with 'kg/cm^2' on them as if this were even a real unit of pressure. It makes me want to scream and start using dodecimeters and heptagrams.

    Between Celsius and Fahrenheit, Fahrenheit makes more sense for _human_ temperature measurements...and if you want to do science it makes more sense to use an absolute temperature scale. Celsius is not part of SI, and enforced metrification to use Celsius is just silly. Use a temperature scale where the triple point of water is 500 units on an absolute thermodynamic scale; then subtract 500 to get the 'human' version.

    The selection of the length of the meter is historic, an itself no better than the foot...in fact I would argue that the unit of length should be 1/1000000000 the distance light travels in a second...which is just about 1 foot!

    On things like wire gauge, AWG is kind of ugly, but an exponential scale makes sense. I'd prefer something where an integral number of gauge counts resulted in an _exact_ doubling of cross section, not the _approximate_ doubling gotten from 3 gauge counts in AWG.

    It goes on. Self consistent units are good, but SI itself was not handed down on high as perfect.

    -Jon

  3. #23
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    And the Metric System is based on the meter... and the second, and the lumen...

    The definitions in the dictionary are more than just the one quoted.

  4. #24
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    Sure as soon as one of the other countries lands a man on the moon.
    What will happen to all the sayings, give an inch take a mile?

  5. #25
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    Quote Originally Posted by winnie View Post
    There are multiple issues here.

    SI is convenient because it is a self consistent system of units. When physics relates two properties, the units are related so that you don't need conversion factors or 'constants' to make the equations work out.

    In SI you can answer F=MA without having to somehow work in '32 feet per second per second' or other similar nonsense.

    But the objection to the _particular_ units selected remains, and the selection was in many ways political.

    Much of the 'forced metrification' uses units that are only vaguely related to SI...places switching from miles per hour to kilometers per hour as if this were meaningful. Pressure gauges with 'kg/cm^2' on them as if this were even a real unit of pressure. It makes me want to scream and start using dodecimeters and heptagrams.

    Between Celsius and Fahrenheit, Fahrenheit makes more sense for _human_ temperature measurements...and if you want to do science it makes more sense to use an absolute temperature scale. Celsius is not part of SI, and enforced metrification to use Celsius is just silly. Use a temperature scale where the triple point of water is 500 units on an absolute thermodynamic scale; then subtract 500 to get the 'human' version.

    The selection of the length of the meter is historic, an itself no better than the foot...in fact I would argue that the unit of length should be 1/1000000000 the distance light travels in a second...which is just about 1 foot!

    On things like wire gauge, AWG is kind of ugly, but an exponential scale makes sense. I'd prefer something where an integral number of gauge counts resulted in an _exact_ doubling of cross section, not the _approximate_ doubling gotten from 3 gauge counts in AWG.

    It goes on. Self consistent units are good, but SI itself was not handed down on high as perfect.

    -Jon
    I don't think anyone would claim that it is perfect. It is just so much simpler.
    Si hoc legere scis nimium eruditionis habes.

  6. #26
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    Quote Originally Posted by MAC702 View Post
    And the Metric System is based on the meter... and the second, and the lumen...

    The definitions in the dictionary are more than just the one quoted.
    I'll try this again. The metre is a unit of length. You can't measure a kilogram in metres.
    It's SI.
    Si hoc legere scis nimium eruditionis habes.

  7. #27
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    I will just say this... when buying cement I think in terms of feet, square feet , yards, square yards, cubic feet, cubic yards, and tons. I cannot think of it in meters, or cubic meters... I have tried, but cannot. Yet, I have no problems in rough figuring rooms at 2.44 meters in height, counters as being 50 pr 60 cm wide, etc..,
    i actually prefer using combinations of feet and meters when measuring furniture in carpentry, etc, and most of my architectural drawings use both metric and imperial, in different colors... I actually own t bars and such in both formats, metal rulers in both formats, etc.
    Because I have done work in so many areas, in so many formats, I don’t think about it too much. Rough carpentry I do in feet but when I try to make a dresser drawer or a fancy door, I switch to metric, and never think about it... I can get more accurate cuts by using metric, and it is easier for me to lay out a room in metric, given more and more tiles are set and sold in metric based sizes.
    So, now I just need to find a way to put the NEC wire tables in my books using the metric wire sizes like used in Europe and Jamaica, and then also do the conduit tables the same way... because unfortunately for me, suppliers in Jamaica get whatever supplies they can get, and have a take it or leave it attitude so one can start a project with US conduits, outlet boxes, and wire, halfway through the project only find Canadian parts, and suddenly the only wire available is European... unless one wants to wait for a few months or pay for a special shipment... the joys of living in the third world.
    So, knowledge of the correct conversions from 12 gauge to 2.5 or 4mm wire, or how many 12 gauge wires fit in a fifteen mm conduit compared to a 1/2 inch conduit... difference may not seem like much but there are differences.
    Student of electrical codes. Please Take others advice first.

  8. #28
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    Quote Originally Posted by Besoeker View Post
    I'll try this again. The metre is a unit of length. You can't measure a kilogram in metres.
    It's SI.
    Ah, but you can. A cube of pure water 1 cm on a side masses one gram.

  9. #29
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    Quote Originally Posted by Besoeker View Post
    I'll try this again. The metre is a unit of length. You can't measure a kilogram in metres.
    It's SI.
    Metric-noun : A decimal unit of measurement of the Metric System (based on meters and kilograms and seconds)
    The Sage's English Dictionary and Thesaurus
    If you aim at nothing, you will hit it every time!

  10. #30
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    First we must collectively agree that facts exist...
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