[AJames]

Hi All

I continue to be amazed at the support for the imperial system here, which in Australia is almost totally accepted. I think the problem is not that the imperial system is necessarily good or bad, but that it is almost useless in calculations of even the simplest kinds. Moreover, there are no problems in say; feet, miles, or degree Fahrenheit, but the real problem is in calculating secondary units like pound force and the dyne.

For example, measured force has the SI unit of the newton (symbol N), equivalent to kg·m·s^−2. The earlier CGS unit is the dyne. Simply, these units are easily calculated using Newton law, F=m times a
(force equals mass times acceleration).

Unfortunately, in the Imperial units, if F is measured in "pounds force" or 'lbf', and a in feet per second squared, then m must be measured in slugs. Similarly, if mass is to be measured in pounds mass, and a in feet per second squared, the force must be measured in poundals. The units of slugs and poundals are specifically designed to avoid a constant of proportionality in this equation.

Now this is really nuts, because you have to have a secondary understand just to do simple calculations in imperial units.

Ie.
1 dyne = 10^-5 newtons
1 kgf (kilopond kp) = 9.80665 newtons
1 lbf = 32.174 poundals
1 slug = 32.174 lb
1 kgf = 2.2046 lbf

In metric, all you have to know is the acceleration due to gravity, which is 9.80665 m/s² and you can do all the force calculations you want - and without any conversions with difficult manipulations.

It is for this reason why in America and the UK, that scientific or engineering have readily dumped the imperial system all together. Yet the basic everyday units remain, just because they feel comfortable and convenient. However, when calculations are involved, we end up in a total mess having endless conversions factors. The advantage of metric units is that no conversions other than knowing multiples of base 10 - and this is why it was adopted in Australia beginning in 1966, with the legislation being unanimously approved in 12 June 1970. The general public only saw the changes when the retailers were force to adopt the metric system in 1974-75, where it became against the law to use imperial measures.

The real reality is that; English has become the language of commerce, the metric system has become the language of measurement.

You can read about the rationale behind Australia history in this regard at;
http://www.mail-archive.com/usma@col.../msg18205.html

To our non-Australian reader here, the comment about especially towards the US avoiding metrification that happened in Australia from 1968 can be summed up as;

"Resistance to the metric change is mostly due to fear of the unknown.
Few realised it could be a simple, non-traumatic experience so that, with
the general public, support for the change can only be expected after it has
been experienced, as was the case with the adoption of decimal currency."

Andrew

Note: While I've been hammering the US and UK, actually, only two other countries haven't adopted metrification being Liberia and Burma.