SI Measurement in Engineering Textbooks

<p>Does it make any sense for a U.S. undergraduate engineering major to use the International Edition of a textbook wherein the problems/numerical examples in that textbook are metric rather than the standard U.S. measurement system? I notice that sellers of such versions offer them at a fraction of the cost of the U.S. edition, even when the International Edition is printed on the same high quality paper (and in color) as the U.S. edition of the book.</p>

<p>Most “US versions” of textbooks don’t use US customary units either. The vast majority use SI. Why? Because US customary units are garbage for engineering and scientific calculations.</p>

<p>Boneh3had, I was hoping you’d jump in. I always find your posts very relevant and informative.</p>

<p>I’m no engineer but I had an inkling that makes me feel your statement about the engineering profession in the U.S. and the metric system is true. I was thinking, ‘if nearly EVERY consumer good that one purchases in U.S. stores these days has a metric system measurement attached to it, then by God what sense does it make for engineers to use the U.S. standard measurements when creating really critical stuff?’ I don’t care whether or not the deep fryer jockey at Mickey D’s uses ounces or grams to fill my bag of fries, but I’d sure as shootin’ be skeptical about a new bridge or auto part or medical device etc. if there was some mistranslation over the measurements.</p>

<p>Oh don’t get me wrong, many engineering firms still do a lot of things in US customary units an it annoys the dickens out of a lot of younger engineers. There are a lot of legacy codes and engineers who is them so the companies keep doing it. By and large though, textbooks focus on SI units.</p>

<p>US costumary is a waste of space</p>

<p>90% of the time all of my engineering classes used SI. Rarely did I ever see a lb/in^2 on a test. Had a slug once though. International editions saved me a lot of money.</p>

<p>Most structural engineers in the US never use the metric system. Well, I guess I did one project in the 90s that required it, but that was the exception. We would LOVE to switch, because it’s a pain in the read to add numbers such as 45’-1 1/16" and 93’-9 7/8" all the time. Blech!</p>

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<p>Being in the construction industry, everything I’ve seen is in US customary units, with exceptions being specialty products from overseas. That goes for everything from foundations to finished architectural items.</p>

<p>The other semi-exception was when I worked for the state department of transportation. Everything the state used was in metric, but the contractors always used US customary. I was working as an inspector at the time and that was such a pain. I had to convert so often that I taped a small chart to my tape measure. </p>

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<p>This is probably why civil engineering mainly uses US customary as opposed to metric; everybody downstream uses it, including the architect, contractors, and the end-users.</p>

<p>My high school AP physics class only uses SI units, it’s a lot easier than US units.</p>

<p>I’ve had classes conducted almost entirely in English system units.
It’s a needless pain that serves no real purpose. I suppose it’s because that’s what they use in the US, but that’s just a matter of unit conversion.</p>

<p>I just make it a practice that, when working with companies that use US customary units, I still do all my work in SI units and then just convert to US customary units for the PowerPoint. The SI system is so self-consistent and plays nicely with equations and modeling due to its nice scaling that I just don’t see a reason to do calculations or modeling or measurements in US customary units. You have to be careful doing that or you may pull a NASA and crash a probe into Mars, but I still prefer that approach.</p>

<p>Honestly, US customary units can die in a fire. That is how I feel about them… unless I am driving.</p>

<p>Brother in law is a structural engineer, has been for at least 25 yrs. I seem to remember him mentioning a few years back that getting government contracts required us of SI units? I distinctly remember him saying that he has to start thinking in terms of kilopascals, as opposed to psi.</p>

<p>Does any of this have a ring of truth to it???</p>

<p>MADad, there is absolutely some truth to that. However, that does not mean the contractors work in SI in the field. The people in the middle get stuck doing conversions.</p>

<p>We just issued structural drawings for a project at the Portsmouth Naval Shipyard, and everything was in US units. I’m sure some government contracts require SI, but we haven’t done any of them. Maybe once we qualify as a woman-owned business, we’ll go for some of those!</p>

<p>To clarify for everyone here, they are not “US Customary” units. From now on, please refer to them as the “British System (BS)”</p>

<p>BTW - I work with both. I deal will a lot of old systems that were designed and built before the US ever gave any serious thought to using SI units. New stuff is almost always SI. It is worth being comfortable with both.</p>

<p>I refuse to refer to it as the British System despite the initials, as the British haven’t used that system for some time. I don’t want to unneccesarily drag them through the mud like that. ;-)</p>

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If the text is just for self-teaching, sure. If used for problems, this is an issue.</p>

<p>Most US-edition texts I’ve seen use both SI and imperial units, varying by problem.</p>

<p>My education was all in SI units, but professionally we interface with other industries and therefore use their standards. As an example, pilots measure altitude in feet or kilofeet (yes, really), so we plan and present a lot of our aerospace products in those units.</p>