1. Review

2. Review Topics 1.Today: Review and Quiz 2.Test on Monday

3. Review Topics 1.Quantity, Units, Prefix, symbol, conversions 3. Rules of Significant numbers and calculations 5. Precision and Accuracy 7. Reading Scale 9. Uncertainty

5. How to Review 1.Experts stay in their station 2.Group members talk and expert collect info and write 10 points on the topic 3.Group members move to other groups after 5 minutes. Experts don’t leave their stations. 4.There will be four rounds of discussion, each of 5 minutes. 5.Experts come and present their points

6. 1. Quantities, Units, Prefix

7. SI (International System) Base Units QuantityWritten UnitUnit Symbol Lengthmetrem Massgramg Timeseconds Amount of substance molemol volumelitreL

8. Magnit ude PrefixUnit Expone nt SymbolNameSymbolname 2.510 -2 CCentiMmeter 2.5 cm

9. 5. Convert 65 m 2 to mm 2 ( ) 2 mm 2 1 m 2 x 1 x 10 3 = 6.5 x 10 7 mm 2 65 m 2

10. Given that:2.21 lb = 1.00 kg4.54 L = 1.00 gal 1.00 atm = 101.3 kPa1.61 km = 1.00 mile 14 lb = 1 stone2000 lb = 1 ton 16 oz = 1 lb 4. 152 mL to gal = 3.35 x 10 -2 gal 4.54 L x1 gal 1000 mL x 1 L152 mL Round to 3 sig figs

11. Derived Quantities

12. 3. Determine the mass of a 85.0 cm 3 sample of lead. Do some research to find density of lead. Density = 11.34 g/cm 3 85.0 cm 3 x 11.34 g = 964 g 3 sig. figs. 1 cm 3

13. 2. Significant Numbers

14. Significant figures The number of meaningful digits in a measurement including the uncertain digit. “sig figs” 2.50025 0.006503 50014 0.02003006 0.020104 2001 200.3 2.0 x 10 2 2 2. x 10 2 1

15. Types of Numbers Measurements 2.5 cm long Use sigfig rules Defined Numbers I min= 60 s Do not use sigfig rules Countable 25 students Do not use sigfig rules

16. Multiplying and Dividing with Significant Figures When multiplying or dividing numbers round the answer to the least number of significant figures found in any of the numbers used. 1. V=distance time V=25.3698 m=13 m/min 2.0 min 6 sig figs 2 sig figs

17. Adding and Subtraction with Significant Figures When adding or subtracting numbers round the answer to the largest decimal place found in the uncertain digits of any of the numbers used. 3. 301.2256 - 0.36 300.87the largest decimal is the second

18. 3. Precision and Accuracy

19. Types of Numbers Inexact Numbers Measurements 2.5 cm long Use sigfig rules Exact Numbers Defined Numbers I min= 60 s Do not use sigfig rules Countable 25 students Do not use sigfig rules Have uncertainty

20. Precision vs. Accuracy Precision –how closely individual measurements agree with each other Accuracy –how closely individual measurements agree with the correct or true value Good precisionGood accuracy and precision Neither

22. Precision vs. Accuracy

23. 4. Reading Scale

24. HOW TO READ A SCALE How to Read Scale(Sigfig) Certain Number Numbered Divisions Un-numbered Divisions Uncertain Number One uncertain number

25. HOW TO READ A SCALE Reading of scale must include three kinds of numbers. 1.Numbered Divisions 2.Unnumbered Divisions 3.Guess (uncertain)

26. 5.08 cmone uncertain 5. cm all certain 5.0 cmall certain

27. 5. Uncertainty

28. HOW TO CALCULATE UNCERTAINTY Only last digit is uncertain. Never write like this 2.50 0.2cm Decimal places of uncertainty MUST match the decimal places of the reading

29. Uncertainty Calculation MeasurementsRangeScale Average ± farthest Unit

30. Determine the average and uncertainty 5.1.263 cm 1.262 cm 1.261 cm 1.273 cm 1.262 cm 1.262  0.001 cm

31. Uncertainty Calculation MeasurementsRangeScale Average ± farthest Unit

32. Exploring and Dealing with Uncertainty of Range A measurement is in the range from 0.5128g to 0.5132g. what is uncertainty of the measurement? Find mean: (0.5128 + 0.5132)/2 = 0.5130g Find difference in the reading = 0.5132 - 0.5128 =0.0004 g Divide the difference by 2 = 0.0002 Now answer should be 0.5130  0.0002 g

33. Uncertainty Calculation MeasurementsRangeScale Average ± farthest Unit

34. Exploring and Dealing with Uncertainty of Scale 1.If a scale has 5 unnumbered divisions then uncertainty is 2 2.If a scale has 10 unnumbered divisions then uncertainty is 1 3.If a scale has 2 unnumbered divisions then uncertainty is 5 Now go to page 32 and find uncertainty of the scales given in question 48