advertisement

WU 8/31 • Create the following data table in your notes. Measurement Number of paperclips Length of pen/pencil Volume in beaker Volume in graduated cylinder Temperature of water Value WU 9/1 **Take Out HW** 1. Read page #1 of the Syllabus 2. What category of this class has the most effect on your grade? 3. When you walk into the room each day, what is expected of you? 4. As simply as possible, state the tardy policy for this class. 5. What is the policy on late work? 6. What is the URL for the class website? WU 9/2 • Adjust your data table from yesterday. Measurement Number of paperclips Length of pen/pencil Volume in beaker Volume in graduated cylinder Temperature of water Value New Value # Sig. Figs In your notes… • Write what you think the word significant means. 3-1 Significant Figures • Measurements have some uncertainty. • When taking a measurement, significant figures are : –all the digits that are known, –plus one digit of uncertainty, or a guess. Rules for significant figures: 1. EX: 4.564 has ____ significant figures – Every nonzero digit in a reported measurement is assumed to be significant. – 5.62 has _____ significant figures. 2. EX: 4.056 has ____ significant figures • Zeros between nonzero digits are significant. • EX: 5.0725 has ___ significant figures. Rules 3 and 4 3. EX: 0.000435 has _____ sig. figs. –Leftmost zeros in front of nonzero numbers are not significant. –EX: 0.0021 4. EX: 5.0540 has _____ sig. figs. •Zeros at the end of a number to the right of a decimal place are significant. •EX: 9.210500 Rule 5 EX: 50400 has _____ significant figures. – Zeros at the end of a measurement, to the left of a decimal place are not significant. – If a decimal place is included after the zeros, count the zeros as significant. – EX: 649000. has _____ significant figures. Rule 6 EX: There are 34 students in this class • Given values, or exact quantities have infinite significant figures Practice • How many sig figs are in the following numbers? - 3.0345 - 6.230 - 0.0000678 How many significant figures are in the following measurements? a. b. c. d. e. f. 5.6780 g 0.00381 s 679000.0 m 6.0834 kg 5 apples 3.000 cm a. 5 b. 3 c. 3 d. 5 e. Infinite f. 4 Significant Figures & Math • In General: calculated measurements are only as good as their weakest link (fewest sig figs) • Addition & Subtraction – round answer according to fewest decimal places. (Don’t count digits to the left of the decimal place) • Multiplication & Division – Round answer according to fewest significant figures in measurements (Count ALL digits) • **These rules are on p. R60 as well