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Error in Measurement

Error in Measurement. Some error or uncertainty always exists in any measurement. skill of the measurer limitations of measuring instruments When recording measurements, report all digits known for certain plus one last digit that is an estimate. Recording Measurements.

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Error in Measurement

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  1. Error in Measurement • Some error or uncertainty always exists in any measurement. • skill of the measurer • limitations of measuring instruments • When recording measurements, report all digits known for certain plus one last digit that is an estimate.

  2. Recording Measurements • Record the volume of liquid in the graduated cylinder to the correct number of digits.

  3. RULES FOR DETERMINING SIGNIFICANT FIGURES • Rule #1: Nonzero digits always count as significant figures: Examples: 438 g _____ sig fig 26.42 m _____ sig fig 1.7 cm _____ sig fig 0.653 L _____ sig fig

  4. Rule #2: Captive zeros always count as significant figures: Examples: 506 dm _____ sig fig 1005 mL _____ sig fig 900.43 kg _____ sig fig 20.006 cm _____ sig fig • Rule #3: Leading zeros do not count as significant figures: Examples: 0.8 g _____ sig fig 0.06 g _____ sig fig 0.0047 L _____ sig fig

  5. Rule #4: Trailing zeros are significant only if the number contains a decimal point: Examples: 60 g _____ sig fig 4830 km _____ sig fig 8.0 dm _____ sig fig 1.60 sec _____ sig fig 35.000 L _____ sig fig 0.002450 kg _____ sig fig

  6. RULES FOR ROUNDING OFF NUMBERS • If the digit immediately to the right of the last significant figure you want to retain is: • Less than 5------ the last significant digit should stay the same. Example: Round 17.32 m to 3 significant figures. • Since the 2 is less than 5, you should round to __________ m

  7. 5 or greater --------- the last significant figure should increase by 1. Example: Round 42.68 g to 3 significant figures. • Since 8 is greater than 5, you should round to __________ g

  8. What Do You Think? • Determine the number of significant figures in each of the following: a. 12.045 d. 12.0 b. 0.0028 e. 0.500 c. 6500 f. 16.002070 • Round each of the following to 2 significant figures. • 5.2836 b. 0.06382 c. 3196 • Explain how the measurement 6.2 cm is different from 6.20 cm.

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