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Re: [Phys-l] Sig figs

Hi all-
I don't know about chemistry, but I learned as an engineer that the difference between telling a machinist that the dimension you want
is 1.011", as opposed to 1.0", may be a big part of your annual budget.
Jack "Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley

On Wed, 13 Oct 2010, Josh Gates wrote:

Wow, that's interesting - some sort of font problem, perhaps? The quoted material was in a different font (from the copy and paste)... Let's try this:

From: Josh Gates []
To: Forum for Physics Educators []
Sent: Wed, 13 Oct 2010 07:52:21 -0400
Subject: Sig figs

Not to wave a flag in front of a bull, but I had to tell someone about this:

From Walker, 4th edition solution manual, 2(18):
"Insight: This problem illustrates the limitations that significant figures occasionally impose. If you keep an extra figure in the total elapsed time (1.09 h) you’ll end up with the time elapsed for the car trip as 0.25 h, not 0.3, and the speed of the car is 64 km/h. But the rules of subtraction indicate we only know the total time to within a tenth of an hour, so we can only know the time spent in the car to within a tenth of an hour, or to within one significant digit."

Insight, indeed.

I had to come here, because my chemistry colleague is a sig figs devotee. He has done quite a bit of "real chemistry," and tells me that he uses sig figs in work for publication - does anyone know if that's the standard expectation in chemistry journals, or is it just not important, if you're publishing a characterization of some previously-undescribed plant aroma molecule or describing a new synthesis process for something?


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