ecology665

I would like to Thank You all (Timo, Sensei, John Cuthber, and Swansont) for your comments they were very helpful. For those of you who wonder why I asked. Yes, the textbooks vary in years of copyright. For example, Physics for Scientists and Engineers by Serway & Jewett (copyright 2014) has atomic mass unit 1.660 538 782 (83) x 10-27 kg, Physics for Scientists and Engineers by Giancoli (copyright 2000) has amu at 1.6605402 (10) x 10-27 kg. Chemistry by Reger, Goode & Ball as amu at 1.660 539 x 10-27 kg. There are variations in most of my textbooks for the constants. Sensei, I just finished precalculus last winterim term. I have a choice of Calculus 101 or physics without calculus. I noticed that the information enclosed either in the inset of the front and back of textbooks along with the appendices is information that you need to know or how to derive at attaining it be it formulas or functions. Timo, Thank You for explaining the uncertainty of the given intervals.

Hello Everyone, I am an undergraduate studying - Environmental Science. My question is whose formula do I use? I used mnemonics to learn the Fundamental Constants from a Chemistry book only to find the numbers are different in the other Chemistry textbooks, and Physics textbooks that I have. I found a website 'physics.nist.gov' and they have even different numbers for the constants? I am confused. Should I go ahead and re-learn the numbers the physics website gives? (I don't want to bump head with a professor who governs from the textbook.) I have yet to take Calculus, so I don't understand the numbers in parenthesis for formulas? For example, Electron mass - me is 9.109 382 15 (45) x10-31 kg. What does the (45) represent?