Here are some thoughts on units of force:
In the metric system, the unit of force is given as the unit of mass times the unit of length over the unit of time squared. (N=kg m/s^2) Therefore, if you have a mass and a speed, no conversion factors are necessary to find its force. Just multiply.
In the English system, a conversion factor is necessary. This is the conversion factor between pounds mass and pounds force. However, this conversion factor equals the acceleration of gravity on the surface of the earth! Therefore, in the English system, you have the following. When an object is moving at an arbitrary speed, you have to do an extra calculation, but when it is falling on earth, the two cancel out and you don't have to do any calculations at all! Considering that much of the time when you are dealing with a moving object it is falling under earth's gravity, this makes calculations much easier. SI is techincally more rational, but English is often more convenient, even for scientific calculations.

Why do I always forget to title my messages...
Sorry about that

Bud wrote

<<
However, this conversion factor equals the acceleration of gravity on the surface of the earth!
>>

The accelaration due to gravity is not constant. At the poles it is about 9.83 m/s^2 while at the equator it is about 9.78 m/s^2. This is one of the shortcommings of the ENglish system

This is a difference of less than half a percent, and that too in the most extreme of locations.
For most calculations that engineers do, this can be neglected.
Even if it were not negligible, I don't see how it can be called a shortcoming of the English system, because the SI system offers no improvement.

Technally bud, your point is actually valid and true. But also technically it is not:

English- Pound mass with unit force poundal; Slug mass with unit force pound-force

Metric- Kilogramme mass with force unit newton; TGME mass with force Kilogramme-force.


Though, as you say, comonly it is the pound-mass and pound-force that are used. Whereas in metric it is almost always kilogramme mass and newton.



However, in the system I outlined before, where the length unit = 24" EXACTLY, the time unit = 1/4sec EXACTLY, gravity accelerates at 1.005 length units per time unit squared. :)

Yes!! What he failed ot mention, Bud, is that the Earth flattens relatively dramatically at the poles, and bulges not inubstanitally at the equator. In other words, that half-percent is still far more than the reality of the situation, in any case!!

On a related note, in this new system of mine (where mass unit also equals EXACTLY 8oz avoird.), my vital stats are now:


3 length units 1 inch high
340 mass units (marks)


also, weight of air (or whatever you call it-- 14.69lbf) = 29.5mk-f. Hmmm, isn't this very close the pressure of it all in inches to? Like 29.92, isn't it?

Hardly anybody has heard of the slug. According to my prof, it is never used in industry. It was created by academics who were trying to make the English system like SI.
And what is a TGME?

Sorry, typo. I meant TME. It is the "metric slug" of 9.80665kg-mass.


The slug was invented- or rather called by THAT name- in 1903, as I recall; hardly an imitation of the not even invented SI. Regardless, I take your point.


Still ,what do you think of such a system where:

Mass unit = 8oz EXACTLY
Length unit = 24" EXACTLY
Time unit = 1/4sec EXACTLY

In such a system:-
* the cube of the length unit filled with water has a mass of 1000 mass units
* gravity accelerates at almost exactly 1 length unit per time unit squared

Personally, I feel that most of the reasons for not metricating would be defeated if we modified the customary system in any significant way.

Bud,
You are assuming that the issue can be resolved by comparing the merits of the system. In fact, merit has nothing to do with it; metric is about pressure to conform.
Admittedly, the name of the forum is the Great Debate, but perhaps it is the wrong debate.

Hmm, I would say a system where time unit = 0.25secs, mass unit = 0.5lb & length unit = 2ft is a good one as it offers a big improvement over metric and English WHILST BEING ***COMPLETELY*** EASILY USABLE IN A NATION WITH ENGLISH UNCHANGED. As I say, the mass unit is EXACTLY 8oz, the length unit EXACTLY 24", the time unit EXACTLY 1/4secs- no fiddling is required, and we end up with a very good system.