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22 Sept. 2010

22 Sept. 2010. Take out homework: Week 2/3 Homework p. 3 Analysis for graphs Objective: SWBAT determine the precision and accuracy of data. Do now: Imagine you are a very accurate shot with a bow and arrow. Draw a picture to show what your target looks like at the end of practice. Agenda.

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22 Sept. 2010

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  1. 22 Sept. 2010 • Take out homework: Week 2/3 Homework p. 3 Analysis for graphs • Objective: SWBAT determine the precision and accuracy of data. • Do now: Imagine you are a very accurate shot with a bow and arrow. Draw a picture to show what your target looks like at the end of practice.

  2. Agenda • Do now • Go over HW: Analysis of graphs • Notes and examples of precision and accuracy Homework: • Week 2/3 Homework p. 3 Conclusions: Fri. • Conclusion for Density of Pennies Lab: Fri. • Week 3 Homework: Fri. • Lab report: Weds. SWBAT determine the precision and accuracy of data.

  3. Precision and Accuracy • precision: how close a series of measurements are to each other. • accuracy: how close a series of measurements are to the actual or true value. SWBAT determine the precision and accuracy of data.

  4. SWBAT determine the precision and accuracy of data.

  5. Volume of a sample of water(Actual volume: 5 mL) • 2.0 mL, 2.1 mL, 1.9 mL • 4.0 mL, 5.0 mL, 6.0 mL • 1.2 mL, 5.5 mL, 10.6 mL • 4.9 mL, 5.0 mL, 5.0 mL SWBAT determine the precision and accuracy of data.

  6. Mass of copper cylinder (g) Three students made multiple weightings of a copper cylinder, each using a different balance. The correct mass of the cylinder had previously been determined to be 47.32 grams. Comment on the accuracy and precision of each student’s measurements. SWBAT determine the precision and accuracy of data.

  7. Comment on the accuracy and precision of these basketball free-throw shooters: • a. 99 of 100 shots are made • b. 99 of 100 shots hit the front of the rim and bounce off • c. 33 of 100 shots are made, the rest miss. SWBAT determine the precision and accuracy of data.

  8. Percent Error: a measurement of how accurate your data are • So, if the actual value is 5.0 grams, but your average mass was 4.6 grams, what is your percent error? • What if your average volume was 25.0 mL, but the actual value is 23.9?

  9. Homework • Week 2/3 Homework p. 3 Conclusions: Fri. • Conclusion for Density of Pennies Lab: Fri. • Week 3 Homework: Fri. • Lab report: Weds.

  10. 24 Sept. 2010 • Take out homework: Week 3 HW • Objective: SWBAT convert between units in the SI system and review for a quiz! • Do now: My actual mass is 59.1 kilograms. I weighed myself on three different scales at the gym, and got the following masses: • 64.9, 65.0 and 65.2 kg. • Are these masses accurate, precise, both or neither, and WHY?

  11. Agenda • Do now • Homework Check: Week 3 HW • Converting SI units • Review Stations Homework: Finish Week 2/3 Homework Quiz Monday. Bring your book!! (see me after school if you need a book)

  12. Converting between SI units • notes from the board SWBAT convert between units in the SI system.

  13. SI Unit Prefixes

  14. Steps to Conversions • Identify and write your known and unknown. • Choose an equality. • Make a fraction • Put units to cancel on the bottom • Put units to remain on the top • Cancel units and compute • Report answer with units!

  15. Practice Problems • 1 liter = 1000 milliliters • How many liters are equal to 550 milliliters? • How many milliliters are equal to 3.5 liters? • How many liters are equal to 45,000 milliliters? • How many milliliters are equal to 354 liters? SWBAT convert between units in the SI system.

  16. 1 meter = 100 cm, 1 kilometer = 1000 meters • How many meters are equal to 500 centimeters? • How many centimeters are equal to 850 meters? • How many meters are equal to 37.5 kilometers? • How many centimeters are equal to 5.8 kilometers? SWBAT convert between units in the SI system.

  17. Homework Finish Week 2/3 Homework Quiz tomorrow Bring your book!! (see me after school if you need a book) • Lab report: Weds. SWBAT convert between units in the SI system.

  18. 23 Sept. 2010 • Take Out: Week 2/3 Homework You need a calculator and your book. • Objective: SWBAT show what you know about Thinking Like a Scientist. • Do now: How many meters are equal to 37.5 kilometers? (1 kilometer = 1000 meters)

  19. Agenda • Do now • Homework Check • Quiz • Physical properties and changes: textbook reading Homework: Finish Textbook Analysis Classwork and Homework: Mon. Lab Report: Tues.

  20. Quiz Expectations • Work silently and on your own. • Raise your hand if you have questions. • When you finish, flip your quiz over. • Begin working on the textbook analysis classwork.

  21. Homework Finish Textbook Analysis Classwork and Homework: Mon. Lab Report: Tues. Please bring a calculator EVERY day!

  22. 24 Sept. 2010 Grab your clicker! Take Out Homework: Textbook Analysis Objective: SWBAT identify and round a number to the correct number of significant figures. Do now: What is the difference between chemical and physical changes? SWBAT identify and round a number to the correct number of significant figures.

  23. Agenda • Do now • Homework check • Notes: Significant Figures • Practice Problems • Conversions problems with significant figures Homework: Sig. Fig. and Rounding Worksheet Lab report: Tues. (typed) SWBAT identify and round a number to the correct number of significant figures.

  24. An engineer was responsible for calculating amount of water that overflowed from a dam. He measured all of the water runoff going into the reservoir (1.2 million cubic feet per year), the rainfall (860 cubic feet per year), and the capacity of the reservoir (3.8 million cubic feet). He did some fancy calculations. He reported to his boss that the overflow from the dam would be 350,246.2544330 cubic feet per year. • What’s wrong here? SWBAT identify and round a number to the correct number of significant figures.

  25. Significant FigureS Rules for determining how many digits to round to

  26. I. Significant Figuresaka: Significant Digits • A. Nonzero integers count as significant figures • Ex. Any number that is NOT zero (1, 2, 3, 4, 5, 6, 7, 8, 9) • 345 • 597.2 • 145.456 SWBAT identify and round a number to the correct number of significant figures.

  27. Zeros • B. Leading zeros that come before all the nonzero digits do NOT count as significant figures • Ex: 0.0025 has two sig. fig. The zeros are “leading” and do not count. • 0.23 • 0.0004 • 0.03564 SWBAT identify and round a number to the correct number of significant figures.

  28. C. Captive zeros are between nonzero digits and DO count as sig. fig. • Ex: 1.008 has four sig. fig. The zeros are captive and DO count. • 10,004 • 1.000006 • 1,000,000,000,000,567 SWBAT identify and round a number to the correct number of significant figures.

  29. D. Trailing zeros are to the right end of the number and DO count as sig. fig. if the number contains a decimal point. • Ex.: 100 has only one sig. fig. because the trailing zeros DO NOT have a decimal point. • Example: 1.00 has three sig. fig. because the trailing zeros DO have a decimal point. • 1.000000 • 3,000,000 • 3.00000 • 30.00 • 300 • 300. SWBAT identify and round a number to the correct number of significant figures.

  30. E. Exact numbers • Any number found by counting has an infinite number of significant figures. • Ex: I have 3 apples. The 3 has an infinite number of significant figures. • 50 people • 100 baseballs SWBAT identify and round a number to the correct number of significant figures.

  31. Which are exact numbers? • The elevation of Breckenridge, Colorado is 9600 feet. • There are 12 eggs in a dozen. • One yard is equal to 0.9144 meters. • The attendance at a football game was 52,806 people. • The budget deficit of the US government in 1990 was $269 billion. • The beaker held 25.6 mL of water. SWBAT identify and round a number to the correct number of significant figures.

  32. How many significant figures? 256 • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  33. How many significant figures? 647.9 • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  34. How many significant figures? 647.0 • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  35. How many significant figures? 321.00 • 2 • 3 • 4 • 5 SWBAT identify and round a number to the correct number of significant figures.

  36. How many significant figures? 4005 • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  37. How many significant figures? nine • 1 • 2 • 3 • infinite SWBAT identify and round a number to the correct number of significant figures.

  38. How many significant figures? 200. • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  39. How many significant figures? 200.0 • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  40. How many significant figures? 0.009009 • 2 • 4 • 6 • 7 SWBAT identify and round a number to the correct number of significant figures.

  41. How many significant figures? -500 • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  42. How many significant figures? -500. • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  43. How many significant figures? 1.3x1032 • 1 • 2 • 3 • 4 SWBAT identify and round a number to the correct number of significant figures.

  44. How many significant figures? • A student’s extraction procedure yields 0.0105 g of caffeine. • A chemist records a mass of 0.050080 g in an analysis. • In an experiment, a span of time is determined to be 8.050 x 10-3 s. • Rewrite 8.050 x 10-3 so it has three significant figures. SWBAT identify and round a number to the correct number of significant figures.

  45. So how do we use this new skill? • To determine how many digits to round do after making a calculation. • Ex 1: How many liters are equal to 34,500 milliliters? • Ex 2: How many milligrams are equal to 3,000.0 grams? • Ex 3: How many centimeters are equal to 12.000 meters? SWBAT identify and round a number to the correct number of significant figures.

  46. Complete the Sig. Fig. and Rounding Worksheet SWBAT identify and round a number to the correct number of significant figures.

  47. Homework • Sig. Fig. and Rounding Worksheet • Lab report: Tues. (typed) SWBAT identify and round a number to the correct number of significant figures.

  48. The sample of gold contained 1,200,000,000,000,000,000,000,000,000 atoms. • How do we keep track of ALL those zeros? • In chemistry, some numbers are HUGE!

  49. II. Scientific Notation(aka: Exponential Notation) • 8,000,000 = • 0.00012 = • Integer must be 1≤x<10 • Positive exponent: number > 1 • Negative exponent: number < 1 (but > 0!)

  50. 4,500,000 • 3,950,000,000 • 230 • 230. • 0.00000045 • -0.002 • 0.00781

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