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## HOMEWORK:

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**HOMEWORK:**• Read for today: • Chapter 1: all • Chapter 2: sections 1-5 • Read for tomorrow: • Chapter 2: sections 6-8 • HW #2.1: DUE WEDNESDAY • 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 THURSDAY • 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**Uncertainty**• All about uncertainty • ALL measurements have some uncertainty about 11.83 cm between 11.5 and 12 cm about 11.7 or 11.8 cm**Uncertainty**• All about uncertainty • ALL measurements have some uncertainty**Uncertainty**• Exact numbers: • Examples: • 1 foot = • 1 kilometer = • 1 mile = • 24 hours = • Have NO uncertainty because these numbers are DEFINED • Will never affect “significant figures”**Uncertainty**• Counted numbers: • Examples • I have 11 fingers • there are 11 dogs • Also have no uncertainty • Will never affect “significant figures”**Uncertainty**• Measured number • Examples • I live 6 and a half miles away • I drink 1.5 liters of water a day • This bench is… • ALWAYS have some uncertainty to them • Will always affect “significant figures”**Uncertainty and Measurements**• State the digits you can be sure of! • Guess the next digit! (and only the next digit) I KNOW it is between 11 cm and 12 cm measurement: 11.8 cm graduations (marks): 1 cm uncertainty: ±0.1 cm**Uncertainty and Measurements**• State the digits you can be sure of! • Guess the next digit! (and only the next digit) I KNOW it is between 11.8 cm and 11.9 cm measurement: 11.84 cm graduations (marks): 0.1 cm uncertainty: ± 0.01 cm**Uncertainty and Measurements**• State the digits you can be sure of! • Guess the next digit! (and only the next digit) between 500 cm and 600 cm measurement: 520 cm graduations (marks): 100 cm uncertainty: ±10 cm**Uncertainty and Measurements**The final digit in a measurement must ALWAYS be in the SAME PLACE AS, and be a MULTIPLE OF the uncertainty! If your instrument has an uncertainty of ± 0.01 mL, your measurement will end with .00 .01 .02 .03 .04 .05 .06 .07 .08 or .09 If your instrument has an uncertainty of ± 0.2 g, your measurement will end with .0 .2 .4 .6, or .8 If your instrument has an uncertainty of ± 0.005 cm, your measurement will end with .000 or .005**Uncertainty and Measurements**Which of the following would be correct if measured on the ruler below? assume ± 0.1 cm uncertainty a) 1.0 cm b) 1.50 cm c) 1.55 cm d) 1.6 cm e) 2.00 cm