What is the relationship between force (in lbs) and speed?

[Dr.D]

The fact is that imperial units have no place in most science and engineering.

Wow! That's a shock! I've been practicing engineering for over 50 years, using both SI and USC units, and never noticed when I departed fro the straight and narrow. What was I thinking? Fortunately, my superiors must have been just as confused as I was, since they always thought we were doing engineering.

 

[russ_watters]

An interesting comment, Russ. I note in passing that you did not undertake to rebut a single word of what I have written, but essentially said that you simply don't like it. Well, that's certainly your privilege, but not it is not much of a rational argument.

Um...there was more to my post than just those words...

 

[NFuller]

(electricity and magnetism is another matter, and SI certainly works better there)

You forgot about high performance computing, chemical engineering, metallurgy, food process engineering, medicine, pharmaceuticals, forensics, ... and a lot more. Mechanical engineering seems to be the one field that persistently wishes to hold on to USC units. I assume they are just to lazy to update some the tables they use to SI units.

 

[Khashishi]

The fact that the world uses SI is reason enough to use it over Imperial units. Also, I'm sure more Americans know what a kilogram is than a slug. People associate pounds with mass. Yes, it's possible to educate people to use the proper units, but it's perhaps easier to just go metric.

 

[mfb]

For those who are familiar with Greek and Latin prefixes, the whole SI system is inconsistent if you think about it. The "kilogram" is essentially (by the meaning of the kilo-prefix) 1000 grams. Thus, like it or not, the gram is the fundamental unit of mass for SI, not the kilogram.

The US units don't even have such a prefix system. You are complaining about tiny nuisances in one system while ignoring that the other system is not even coherent enough to discuss this question there.
The kilogram is the SI base unit. Don't misrepresent the SI please.

but I have yet to see that one system is any better than the other for work in mechanics (electricity and magnetism is another matter, and SI certainly works better there). I use both equally well, although like @PhanthomJay I hate to have to convert back and forth.

You avoid conversions within the unit system.
The only way to avoid conversions between unit systems is a single standard used worldwide. In other words, adopting the metric system in the US everywhere, because I can guarantee that the rest of the world won't go back to imperial units. It is not an accident that the SI got adopted nearly everywhere.

 

[lekh2003]

Regarding "weight" expressed in kilograms, it is NOT TRUE that 1 kilogram is 1 kilogram * 1 meter/s^2, so this is an inconsistent usage. It is essentially the same mistake made by expressing both force and mass in pounds, only reversed. Who is to say they are more interested in their mass than in their weight? Are they more interested in the pull of the Earth on their bodies and the resultant ache in their ankles and the soles of their feet? Or are they really thinking about how their momentum will be affected in a collision?

I beg to differ with what you are saying.

Firstly, you are saying that the SI system is arbitrary due to the usage of fudge factors to quantify and make sense of the units. This logic is inherently flawed since everything we observe about the universe is then a fudge factor. We make sense of different things with prefixes and units, because there is no universal system to make everything magically work. The US system and SI system are equally as arbitrary and useless as each other, but if the SI system is easier to use, then let us use it.

Secondly, these so called "inconsistencies" are not a product of the SI system, but a misconception created by the common public without any technical understanding. From a purely technical point of view, I understand the differences in weight and mass, and I'm sure anyone on this forum definitely does. If somebody doesn't, it isn't a fault in the SI system, it is a fault of the people and their linguistic assumptions.

Any units system is a construct of our imagination. This is the way humans understand the world. If one of the methods is easy to convert with, regardless of it's fudge factors, why shouldn't we use it?