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# HOMEWORK:

HOMEWORK:. HW #2.1: DUE THURSDAY Chap. 2 : 5, 7, 8, 11, 13, 33, 35, 37, 38, 39, 40, 43, 45, 47-52 (all), 97, 137, 139, 140 HW #2.2: DUE MONDAY 6/16 Chap. 2, #s 57-63 (all), 65, 67, 69, 71, 73, 79, 82, 85, 87, 89, 91, 92, 93, 95, 101, 105, 109, 143, 153 For lab tomorrow (dry lab)

## HOMEWORK:

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### Presentation Transcript

1. HOMEWORK: • HW #2.1: DUE THURSDAY • Chap. 2: 5, 7, 8, 11, 13, 33, 35, 37, 38, 39, 40, 43, 45, 47-52 (all), 97, 137, 139, 140 • HW #2.2: DUE MONDAY 6/16 • Chap. 2, #s 57-63 (all), 65, 67, 69, 71, 73, 79, 82, 85, 87, 89, 91, 92, 93, 95, 101, 105, 109, 143, 153 • For lab tomorrow (dry lab) • You must have a scientific calculator!! • Beacon with Heather Baker • Wednesdays in LRC 108 • 1:45 – 3:45 • 4:00 – 6:00

2. Uncertainty and Measurements Which of the following would be correct if measured on the ruler below? (This ruler has an uncertainty of ± 0.02 cm) a) 0.5 cm b) 0.50 cm c) 0.055 cm d) 0.75 cm e) 0.100 cm

3. Uncertainty and Measurements For the graduated cylinder to the right, provide the following information (Uncertainty is ± 0.2 mL for this one) What are the graduations? 1 mL What is the volume? 67.6 mL

4. Scientific Notation – Numbers > 1 Place a decimal so that there is a single digit to the left 1.8900000 18900000 Start counting from the right until you get to the decimal 1. 8 9 0 0 0 0 0 7 6 5 4 3 2 1 This becomes the exponent for “times 10 to the” 1.8900000x107 Remove digits from the right until proper # of sig. figs. 1.8900000x107 1.890000x107 1.89000x107 1.8900x107 1.890x107 1.89x107

5. Scientific Notation – Numbers > 1 Place a decimal so that there is a single digit to the left 7.16110 716110 Start counting from the right until you get to the decimal 7. 1 6 1 1 0 5 4 3 2 1 This becomes the exponent for “times 10 to the” 7.16110x105 Remove digits from the right until proper # of sig. figs. 7.16110x105 7.1611x105 7.1611x105

6. Scientific Notation – Numbers < 1 Start counting from the decimal point to the first non-zero digit. This will be the exponent in the “times ten to the negative” 0. 0 0 0 0 0 0 5 7022169 1 2 3 4 5 6 7 Move the decimal point to the right of the first non-zero digit, drop all of the leading zeros, and add the “times ten to the negative” with the exponent. 5.7022169x10-7

7. Scientific Notation – Numbers < 1 Start counting from the decimal point to the first non-zero digit. This will be the exponent in the “times ten to the negative” 0. 0 0 0 0 9 510 1 2 3 4 5 Move the decimal point to the right of the first non-zero digit, drop all of the leading zeros, and add the “times ten to the negative” with the exponent. 9.510x10-5

8. Did you get it? 5.124x108 6.0x10-4 • 512384000 4 s.f. • 0.0006000 2 s.f. • 0.00251634 5 s.f. • 3540000000 5 s.f. 2.5163x10-3 3.5400x109

9. Significant Figures • Significant figures tell you about the uncertainty in a measurement. • Significant figures include all CERTAIN (known) digits, and ONE UNCERTAIN (guessed) digit 11.84 cm 4 significant figures

10. Significant Figures • Significant figures include all CERTAIN (known) digits, and ONE UNCERTAIN (guessed) digit 520 cm 2 significant figures

11. How many Sig. Figs.? Two rules: • #1) If there IS a decimal point in the number: • Start at right of number and count until the LAST non-zero digit

12. How many Sig. Figs.? 2 3 . 0 0 2 8 0 1 0 9 significant figures 0 . 0 6 8 0 0 4 significant figures 1 0 0 . 0 0 0 6 significant figures

13. How many Sig. Figs.? Two rules: • #1) If there IS a decimal point in the number: • Start at right of number and count until the LAST non-zero digit • #2) If there is NOT a decimal point in the number • Start at left of number and count until the LAST non-zero digit

14. How many Sig. Figs.? 7 4 2 9 3 5 significant figures 2 3 0 8 0 0 4 significant figures 1 0 0 0 0 0 1 significant figure

15. 60020300 12.00500 0.0005 0.10046 6 s.f. 7 s.f. 1 s.f. 5 s.f. Significant Practice 320000 8900. 0.0061000 0.1528 2 s.f. 4 s.f. 5 s.f. 4 s.f.

16. Rounding Numbers • Find the last significant digit. • If the next digit to the right is 4 or less, leave the last significant digit alone. • If the next digit to the right is 5 or more, round the last significant digit up.

17. 0.00259428 (3 s.f.) = 0.00259 0.00259428 (3 s.f.) 54.3675701 (5 s.f.) = 54.368 54.3675701 (5 s.f.) 8265391000 (2 s.f.) = 8300000000 8265391000 (2 s.f.) 0.1659822 (4 s.f.) = 0.166 = 0.1660 0.1659822 (4 s.f.) 0.0005473300 (5 s.f.) = 0.00054733 0.0005473300 (5 s.f.) 2617890100 (6 s.f.) = 2617890000 2617890100 (6 s.f.)

18. Sig. Figs. in Calculations Two rules: • #1) Multiplication and Division • The value in the calculation that has the FEWEST number of sig. figs. determines the number of sig. figs. in your answer.

19. Calculations with Sig. Figs. • Multiplication and division • The value in the calculation that has the FEWEST number of sig. figs. determines the number of sig. figs. in your answer. 1.5 x 7.3254 = 1 0 .9881 = 11 2 s.f. 5 s.f.

20. Calculations with Sig. Figs. • Multiplication and division • The value in the calculation that has the FEWEST number of sig. figs. determines the number of sig. figs. in your answer. 6.127 x 0.0000267030 = 0.000163 6 09 = 0.0001636 4 s.f. 6 s.f.

21. Calculations with Sig. Figs. 927.381 / 456.0 = 2.03 3 730263 = 2.034 6 s.f. 4 s.f.

22. Calculations with Sig. Figs. 0.00159 / 2 = 0.000 7 95 = 0.0008 3 s.f. 1 s.f.

23. Calculations with Sig. Figs. 6 s.f. 3 s.f. = 18 8 99522.37 = 18900000 4 s.f.

24. 890.00 x 112.3 78132/2.50 0.0120 x 48.15 x 0.0087 Some Practice 500 x 0.000230012

25. 890.00 x 112.3 78132/2.50 0.0120 x 48.15 x 0.0087 99950 31300 0.0050 Some Practice

26. 500 x 0.000230012 0.000000025 1900000 0.1 Some Practice

27. Sig. Figs. in Calculations Two rules: • #1) Multiplication and Division: • The value in the calculation that has the FEWEST number of sig. figs. determines the number of sig. figs. in your answer. • #2) Addition and Subtraction: • The LEAST precise value in a calculation tells you the precision of the answer.

28. Precision 347000 347000 is precise to the thousands place 0.000254 0.000254 is precise to the 6th decimal place 10050. 10050. is precise to the ones place 637300000000 637300000000 is precise to the hundred millions place 0.0790000 0.0790000 is precise to the 7th decimal place 0.02 0.02 is precise to the 2nd decimal place

29. Adding and subtracting with sig. figs. 394.0150 + 0.0074121 precise to the 4th decimal place precise to the 7th decimal place 394.0150 394.0150 +0.0074121 + 0.0074121 394.0224121 394.0224121 = 394.0224 answer must have the same precision as the least precise measurement (the 4th decimal place)

30. Adding and subtracting with sig. figs. 0.0025647 + 0.000321 precise to the 7th decimal place precise to the 6th decimal place 0.0025647 0.0025647 +0.000321_ +0.000321_ 0.0028857 0.0028857 = 0.002886 answer must have the same precision as the least precise measurement (the 6th decimal place)

31. Adding and subtracting with sig. figs. 682300 + 5922.60 precise to the hundreds place precise to the 2nd decimal spot 682300 682300 + 5922.60 + 5922.60 NO!!!! 688222.60 688222.60 = 6882 688200 answer must have the same precision as the least precise measurement (the hundreds place)

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