One of the weaknesses of the metric system is that its pristine powers-of-ten beauty was compromised to create units of convenient scale for human activity. Ideally, you'd want 1 cubic-length-unit of water to have a volume of one volume-unit and a mass of one mass-unit. But having a cubic meter of water have a volume of one liter and a mass of one gram would mean that we'd constantly be dealing with milli-, micro-, and even nano- liters and grams. Similarly, the gram is a convenient mass unit for some scientists, but the kilogram is more convenient for most real-world uses, so the latter gets treated as the base mass unit for a lot of purposes.

On Wed, Jul 6, 2016 at 12:50 PM, (via tml list) <xxxxxx@simplelists.com> wrote:
This email was sent from shadowgard.com which does not allow forwarding of emails via email lists. Therefore the sender's email address (xxxxxx@shadowgard.com) has been replaced with a dummy one. The original message follows:

On 6 Jul 2016 at 0:34, Richard Aiken wrote:

>
> On Tue, Jul 5, 2016 at 7:28 PM, (via tml list)
> <xxxxxx@simplelists.com> wrote:
>     This email was sent from shadowgard.com which does not allow
>     forwarding of emails via email lists. Therefore the sender's email
>     address (xxxxxx@shadowgard.com) has been replaced with a dummy
>     one. The original message follows:
>
>     On 5 Jul 2016 at 15:40, David Shaw wrote:
>
>     > Um... According to my sources, 1 hectare is approximately 2.5
>     acres. I > think you're getting mixed up between metres squared
>     and square metres > - 1 hectare is 100m squared, not 100 square
>     metres.
>
>     Ok, that's weird. Because that means that an are is 10mx10m. While
>     a stere is 1m*1m*1m.
>
> Not sure what a "stere" is . . . but since 1 times 1 times 1 equals 1,
> I think there's something wrong there.

The base unit of length in the metric system is the meter. The base
unit of area is the are. A hectare is 100 ares (by definition). The
base units of volume are the liter (well known and originally
intended for liquids (think "quart")), and the rarely used stere
(originally intended for solids (think "cubic yard")).

A liter was defined as both a kilo of water and as 10 cm * 10 cm * 10
cm. (1000 cubic centimeters)

A stere was defined as 1 m * 1 m * 1 m ( a cubic meter.

The are is apparently defined as 10 m * 10 m (100 square meters). A
somewhat odd choice. Not exactly intuitive.

> I think David is saying that a hectare is 100m on a side (e.g. 10,000
> square meters), not 10m on a side (e.g. 100 square meters).

Again, *by definition* a hectare is 100 ares. So that'd be a 10x10
arrangement of 1 are squares.

My mistake was thinking that an are was 1 m^2, rather than 100 m^2.



--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com


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