Metric Conversions Why Because it makes sense Metric

Metric Conversions Why? Because it makes sense!

Metric Prefixes �“Karen Has Damaged Many Little Gifts During Christmas Morning” �Kilo- 1000 �Hecto- 100 �Deca- 10 �Base units: Meters (length), Liters (volume), Grams (mass) - 1 �Deci-. 1 �Centi-. 01 �Mili-. 001 �Order of magnitude = power of ten (count the zeros) �Ex: 10 is one order of magnitude greater than 1 �Ex: 1, 000 is 2 orders of magnitude less than 100, 000

Converting in the Metric System Larger prefix – decimal moves left Smaller Prefix – decimal moves right 1 km =. 62 mi 1 kg = 2. 2 lbs 1 m. L = 1 cm 3 See handout – Copy into notebook/notes

Practice Which of these is the shortest length? 60 mm 0. 060 Km 0. 600 m 6000 cm Which of the following is the largest mass? 1000 mg 5 Kg 800 cg 100 g Which metric distance is equal to 0. 62 miles? 1 mm 1 cm 1 Km 1 m Which of the following conversions is/are incorrect? 1 Km = 1000 m 1 m = 1000 mm 500 cm = 0. 5 m 100 mm = 1 cm Which of the following metric masses is approximately equal to 2. 2 pounds? 1 mg 1 Kg 1 µg 1 g How many millimeters are in one kilometer? How many milliliters are in one deciliter? Convert 75 m. L to cm 3 Convert 350 m. L to L Convert 500 m to Km Convert 0. 050 Kg to g Convert 5. 0 x 103 m. L to L Convert 100 m. L to L Convert 600 Kg to g Which two of these are equivalent lengths? 60 mm 0. 600 m 6000 cm 0. 060 Km In metric, the base unit for length is the ______. In the metric system, the base unit for mass is the ______. The measure of the amount of 3 -D space that an object occupies is known as ____. Which of the following are equivalent lengths? 450 cm 45, 000 mm 45, 000 Km

Significant Figures How precisely can you measure?

Precise vs. Accurate �Precise – how close are your measurements to each other? �Accurate – how close are your measurements to the correct measurement (truth)?

Significant figures �All digits in a measurement that are known for certain, plus the first estimated (uncertain) digit �Sig figs give an indication of the degree of precision for a measurement and/or calculation

Sig Fig rules – KNOW AND USE THEM �Rules for determining how many sig figs are in a measurement: �All non-zero values ARE significant � i. e. 54 mm has 2 sig figs � 5400 m has 2 sig figs �All zeros between non-zero digits ARE significant � i. e. 504 N has 3 sig figs �For numbers less than 1 � Zeros directly after the decimal point are not significant � i. e. 0. 00565 J has 3 sig figs

Sig Fig rules – KNOW AND USE THEM �Rules for determining how many sig figs are in a measurement: ctd �A zero to the right of a decimal AND following a nonzero digit IS significant � 0. 150 m has 3 s. f. � 15. 0 kg has 3 s. f. �All other zeros are NOT significant �If you wouldn’t write the zero in scientific notation, It’s not significant.

Scientific Notation & Sig Figs �Use scientific notation when you need to specify how many zeros are significant: �i. e. write 1500 N with 3 s. f. �The best way to do this is with scientific notation: 1. 50 x 103 N �Write 10600 kg with 4 s. f.

Summary

Sig figs in problems �Many problems will have values that look like they only have 1 s. f. �Assume that all digits in the problems are significant �i. e. if a problem says that and object has a mass of 100 kg, please treat that as 3 s. f.

Sig. Figs in calculations �When adding/subtracting: �Your answer must have the same degree of precision as the least precise measurement (choose the smallest number of decimal places) �i. e. : 24. 2 g + 0. 51 g + 7. 134 g = 31. 844 g → 31. 8 g �When multiplying/dividing: �The number of sig figs in the answer is equal to the least number of sig figs in any of the measurements used in the calculation �i. e. : 3. 22 cm x 12. 34 cm x 1. 8 cm = 71. 52264 cm 3 → 72 cm 3

Examples/ Homework How many sig figs in each of the following? 1. 2. 3. 4. 5. 6. 7. 8. 415. 2 cm 0. 00065 s 1500 g 0. 007250 W 105. 00 cm 15. 035 cm 0. 0560 s 35000 kg 1. 2. 3. 4. 5. 6. 1. 25 cm + 6. 5 cm + 11. 75 cm + 0. 055 cm 2. 32 m. L + 2. 2 m. L + 0. 003 m. L + 72. 55 m. L 36. 5 g + 65. 22 g + 9. 870 g 5. 85 kg x 4. 257 kg x 7. 3 kg 25. 50 m x 12. 057 m x 0. 095 m 25. 32 m. L x 6. 87 m. L x 35. 7 m. L