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AGENDA 1-12-12

AGENDA 1-12-12. Unit 1 Measurement and Matter Test 1/24/12 Notes/handouts Elements Quiz #1-20 on Friday. Measurement Unit. Metrics Scientific Notation Significant Figures Dimensional Analysis Density . Exact vs Measured Numbers.

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AGENDA 1-12-12

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  1. AGENDA 1-12-12 • Unit 1 Measurement and Matter • Test 1/24/12 • Notes/handouts • Elements Quiz #1-20 on Friday

  2. Measurement Unit • Metrics • Scientific Notation • Significant Figures • Dimensional Analysis • Density

  3. Exact vs Measured Numbers • Exact numbers are counts not measurements. Ex. A dozen= 12; a minute = 60 seconds • Measured numbers have some uncertainty because of the measuring device.

  4. Types of Measurement • Qualitative measurement: uses words ex. A yellow-green gas was released. • Quantitative measurement: uses numbers ex. The oxide has a mass of 1.567 grams.

  5. Metric Prefixes • Powers of 10 • Know the Metric Prefix to Power of 10 • Tera(109) to femto(10-15) • Show chart and Practice Examples on board

  6. Metric Prefixes

  7. Precision vs. Accuracy • PRECISION: Replication of results ex. A penny is massed 3 times ---- 2.6g, 2.6g, 2.6g • ACCURACY: True or correct results

  8. Results can be precise, but not accurate. Ex. The penny massed 3 times at 2.6 g was precise, but placed on a faulty balance so the results are inaccurate. • Bull’s Eye Example

  9. Significant Figures (Digits) • The accuracy of any measurement depends upon the instrument and the observer. The digits in an answer which imply more accuracy than the measurements justify are not significant and should be dropped so that those digits which remain represent the accuracy of the original measurement and are called SIGNIFICANT DIGITS

  10. Computation Rules for Significant Digits • 2 Main Rules • Rule #1: Addition and Subtraction Rule: The answer cannot be anymore accurate than the least accurate DECIMAL place of the given • Example: next slide

  11. Rule # 1 50.23 + 23.7 + 14.678 = 88.608 (calculator answer) 88.6 (Rounded answer w/ rule)

  12. Rule #2 Multiplication and Division • The answer cannot be anymore accurate than the least NUMBER of significant digits of the given • Example: 4.8070/1.23 = 3.0908130081 (calculator answer) 3.09

  13. Seven Base SI Units • Length meter (m) • Mass kilogram (kg) • Time second (s)

  14. Amount mole (mol) • Electric current ampere (amp) • Luminous intensity candela (cd)

  15. Temperature Kelvin (K)

  16. Quantity • A quantity includes both a number and a standard unit • Examples: 14.5 g 12 mi • A quantitative measurement!!!!

  17. Percent Error • % Error = error/accepted value x 100 Error = experimental- accepted (+ difference)

  18. DERIVED UNITS • A combination of two or more units. • Examples: Speed miles/hr ft/sec • DENSITY is the mass per volume.

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