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What exactly is a pound? Is it a mass? If not, what is the Imperial equivalent? This confused the hell out of me the first time I took uni physics. I had an old

What exactly is a pound? Is it a mass? If not, what is the Imperial equivalent? This confused the hell out of me the first time I took uni physics. I had an older gentleman teach the class who kept talking about slugs. And just to anger metric people: How heavy is Le Gran K today? (note that I prefer metric) Inches to feet is base 12. Feet to yards are base 3. Feet to Miles is base 5280. WHAT? We can go on and on about the imperial system, and many do. The "funny" fact of the matter is this guy is pontificating mainly because of familiarity, and not any scientific rigor. His best argument is that Imperial measurements are based on eyeballing. So can metric, if you are familiar with them.

sp332 14y ago
A pound (speaking very technically, such that only physics teachers would point this out) is a unit of force, not mass. The "imperial" unit of mass is a slug, which weighs about 32 pounds at sea level. https://en.wikipedia.org/wiki/Slug_%28mass%29 https://en.wikipedia.org/wiki/Slug_%28mass%29 The metric unit of force is a Newton, equivalent to ~3.6 ounces of force.
- TheAmazingIdiot 14y ago
  I well realize that now. Many of us worked with metric in the sciences for our university career, as well as prior high/middle/ele school teachings of metrication. Some of the lesser known units of imperial measure throw us off. I asked him to please explain this unfamiliar unit to us. He was rather surprised we hadn't heard of it prior. One very good thing about metric is that it is precise in the definitions of the units. Hence the distinction between kg and N. Added note: even though pound may be technically a force measurement, it at first confused the hell out of me how a pascal( N/m^2) could be converted to lbs/in^2. I did wonder what exactly a pound was, but soon didn't really care. After all, we didn't really use imperial much, with exception of general "consumer measurements".
mpyne 14y ago
> His best argument is that Imperial measurements are based on eyeballing. So can metric, if you are familiar with them. I think people pushing for metric in the U.S. keep forgetting that they are pushing against the status quo. I.e. there must be a positive net benefit to the change they want for there to be a reasonable shot at getting the vast entrenched infrastructure of units displaced. Saying "but but metric can do this too!!" isn't good enough. Metric needs to be better and the fact of the matter is that U.S. imperial units are good enough for the day to day life of the average citizen (who for the most part don't even go around converting imperial units, making any improvement in how conversions can be calculated a moot point).
- TheAmazingIdiot 14y ago
  My funny jab about Le Gran K goes back to the similar reason why Imperial measurements were dumb: the damned measurement (weight) changes. Le Gran K is a weight stored in France that every kilogram weight is measured against. This weight, made of iridium and platinum is measured every 40 years. Every weigh in has been different. Every other metric measurement is keyed in upon a hard constant of nature. A meter is some fraction of C. A second is the number of vibrations in a rarefied caesium gas. The kilogram is a weight that's compared to a bunch of others?! I do remember some chemists working back in '08 about the calculation of a precise kilogram by definition of the exact number of atoms of carbon-12 in a cube. They worked out the math, and determined an exact number of atoms.* * http://gtresearchnews.gatech.edu/newsrelease/kilogram.htm http://gtresearchnews.gatech.edu/newsrelease/kilogram.htm
- VLM 14y ago
  "who for the most part don't even go around converting imperial units" This is the key line which MUST be understood, no matter which side of the argument you're on. Its a sig fig issue. Converting feet to miles is a nearly useless activity. A mile is the minimum human discernible distance for a marching roman legion, in that no human can tell the difference between a 8.2 and a 8.3 mile march at the end of the day, but most can, at the end of the day, tell the difference between 8 and 9 miles of march. So the minimum human sized unit for marching distance is the mile. Ditto degrees F, although the probably apocryphal story about the local weather fitting in a 0 to 100 degree range is probably almost as good a reason as most humans can not discern temps finer than one degree. Another sig fig issue rears its head where frankly unless you're a pastry chef "any ole cup" is close enough to Plato's concept of the ideal form of a cup or a chemists concept of a graduated cylinder for successful cooking or virtually all dishes. If your soup turns out foul its because of substandard ingredients or technique, not because you used 1001 ml of water instead of 1000 ml. I like metric as a conformity thing in science and engineering, but its not inherently any better. You can do useless things that almost no one ever needs to do easier in one system or another, but it doesn't matter most of the time, so just conform and when in rome do as the romans do.

sp332 14y ago

A pound (speaking very technically, such that only physics teachers would point this out) is a unit of force, not mass. The "imperial" unit of mass is a slug, which weighs about 32 pounds at sea level. https://en.wikipedia.org/wiki/Slug_%28mass%29 https://en.wikipedia.org/wiki/Slug_%28mass%29 The metric unit of force is a Newton, equivalent to ~3.6 ounces of force.

TheAmazingIdiot 14y ago
I well realize that now. Many of us worked with metric in the sciences for our university career, as well as prior high/middle/ele school teachings of metrication. Some of the lesser known units of imperial measure throw us off. I asked him to please explain this unfamiliar unit to us. He was rather surprised we hadn't heard of it prior. One very good thing about metric is that it is precise in the definitions of the units. Hence the distinction between kg and N. Added note: even though pound may be technically a force measurement, it at first confused the hell out of me how a pascal( N/m^2) could be converted to lbs/in^2. I did wonder what exactly a pound was, but soon didn't really care. After all, we didn't really use imperial much, with exception of general "consumer measurements".

mpyne 14y ago

> His best argument is that Imperial measurements are based on eyeballing. So can metric, if you are familiar with them. I think people pushing for metric in the U.S. keep forgetting that they are pushing against the status quo. I.e. there must be a positive net benefit to the change they want for there to be a reasonable shot at getting the vast entrenched infrastructure of units displaced. Saying "but but metric can do this too!!" isn't good enough. Metric needs to be better and the fact of the matter is that U.S. imperial units are good enough for the day to day life of the average citizen (who for the most part don't even go around converting imperial units, making any improvement in how conversions can be calculated a moot point).

TheAmazingIdiot 14y ago
My funny jab about Le Gran K goes back to the similar reason why Imperial measurements were dumb: the damned measurement (weight) changes. Le Gran K is a weight stored in France that every kilogram weight is measured against. This weight, made of iridium and platinum is measured every 40 years. Every weigh in has been different. Every other metric measurement is keyed in upon a hard constant of nature. A meter is some fraction of C. A second is the number of vibrations in a rarefied caesium gas. The kilogram is a weight that's compared to a bunch of others?! I do remember some chemists working back in '08 about the calculation of a precise kilogram by definition of the exact number of atoms of carbon-12 in a cube. They worked out the math, and determined an exact number of atoms.* * http://gtresearchnews.gatech.edu/newsrelease/kilogram.htm http://gtresearchnews.gatech.edu/newsrelease/kilogram.htm
VLM 14y ago
"who for the most part don't even go around converting imperial units" This is the key line which MUST be understood, no matter which side of the argument you're on. Its a sig fig issue. Converting feet to miles is a nearly useless activity. A mile is the minimum human discernible distance for a marching roman legion, in that no human can tell the difference between a 8.2 and a 8.3 mile march at the end of the day, but most can, at the end of the day, tell the difference between 8 and 9 miles of march. So the minimum human sized unit for marching distance is the mile. Ditto degrees F, although the probably apocryphal story about the local weather fitting in a 0 to 100 degree range is probably almost as good a reason as most humans can not discern temps finer than one degree. Another sig fig issue rears its head where frankly unless you're a pastry chef "any ole cup" is close enough to Plato's concept of the ideal form of a cup or a chemists concept of a graduated cylinder for successful cooking or virtually all dishes. If your soup turns out foul its because of substandard ingredients or technique, not because you used 1001 ml of water instead of 1000 ml. I like metric as a conformity thing in science and engineering, but its not inherently any better. You can do useless things that almost no one ever needs to do easier in one system or another, but it doesn't matter most of the time, so just conform and when in rome do as the romans do.