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Metric System Basics

Metric System Basics. Metric System. Importance of standard units of measure U.S. is the only major industrialized country in the world not using the metric system What can be measured? Length : distance between two points Temperature : the amount of heat gained or released by an object

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Metric System Basics

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  1. Metric System Basics

  2. Metric System • Importance of standard units of measure • U.S. is the only major industrialized country in the world not using the metric system • What can be measured? • Length: distance between two points • Temperature: the amount of heat gained or released by an object • Mass: the amount of space an object takes up • Time: how long it takes an event (i.e. reaction) to happen

  3. Review of Measurements

  4. Base Units and Metric Measurements • The metric system is based on a base unit that corresponds to a certain kind of measurement • Length = meter • Volume = liter • Mass = gram • The metric system is based on powers of ten: • 10 mg = 1 cg • 10 cg = 1 dg • 10 dg = 1 g • 1L = 1dm3 = 1kg 1kg = 1L = 2.2lbs = 1dm3 • 1cc = 1mL = 1g @ 4°C H2O • (temperature at which water is most dense)

  5. Metric System • The three prefixes that we will use the most are: • kilo • centi • milli

  6. Metric System So to measure length, a meter is the base unit • Length of a tree branch • 1.5 meters • Length of a room • 5 meters • Length of a ball of twine stretched out • 25 meters

  7. Metric System • Prefixes plus base units make up the metric system • Example: • Centi + meter = Centimeter • Kilo + liter = Kiloliter • What if you need to measure a longer distance? For example, what is the distance from your house to school? • Let’s say you live approximately 10 miles from school • 10 miles = 16093 meters • 16093 is a big number, but what if you could add a prefix onto the base unit to make it easier to manage: • 16093 meters = 16.093 kilometers

  8. Metric System • The prefixes are based on powers of ten. What does this mean? • From each prefix every “step” is either: • 10 times larger or • 10 times smaller • For example • Centimeters are 10 times larger than millimeters • 1 centimeter = 10 millimeters

  9. Metric System • Centimeters are 10 times larger than millimeters so it takes more millimeters for the same length 1 centimeter = 10 millimeters Example not to scale 40 41 40 41 1 cm

  10. Base Units and Derived Units Base Units – a unit in a system of measurement that is based on the object or event in the physical world mass (kg) length (m) time (s) temperature (°C) Derived Units – combinations of base units; examples: volume - cm3, dm3 speed - m/s, mi/hr density - g/mL, g/cm3 Standard Units:Mass – kg Volume – L Length – m Time - s

  11. Metric System Kilo 1000 (thousand) Hecta 100 (hundred) Deca 10 (ten) Base 1 (one) Deci 1/10 (.10) (tenth) Centi 1/100 (.01) (hundredth) Milli 1/1000 (.001) (thousandth) **The following are base units: Mass – g Volume – L Length – m Time - s

  12. Metric System Factors The metric system is based off factors of ten: 10 mm = 1 cm10 cm = 1 dm10 dm = 1 m10 m = 1 dkm10 dkm = 1 hm10 hm = 1 km PLEASE COMMIT THE FOLLOWING CONVERSION FACTORS TO MEMORY!! 1g = 1 mL = 1 cm3 10 “milli’s” in 1 “centi” 1000 g = 1 kg 1000 mg in 1 g 100 cg = 1 g

  13. Dimensional Analysis • A problem solving technique that uses conversion factors that equal one • Conversion factors are ratios of equivalent values used to express the same quantity in different units • When you convert from a large unit to a small unit, the number of units must increase. A meter is a much smaller unit than a kilometer, one one-thousandth smaller. So, there are 48,000 meters in 48 kilometers

  14. How to Solve Dimensional Analysis Problems: Example Problem:How many centigrams in 5 grams?1. Write what you know. 5 grams 2. Set up a conversion factor. 5 grams X ________ a. Write what unit you want to get rid of on the bottom of the proportion. 5 grams x ________ grams

  15. How to Solve Dimensional Analysis Problems: b. Write what unit you want to get to on the top of the proportion. 5 grams x centigrams grams 3. Compare the two units in the proportion. A “1” is written next to the bigger unit. Then ask yourself, how many of the smaller units are in the bigger unit? Write that number on the other side of the proportion. 5 grams x 100 centigrams 1 gram 4. Solve. (5 x 100) = 500 centigrams 1

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