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UNDERSTANDING AND USING THE METRIC SYSTEM

UNDERSTANDING AND USING THE METRIC SYSTEM. A. INTERNATIONAL STANDARDS B. EASE OF RECORDING C. EASE OF CALCULATIONS. II. UNITS OF MEASUREMENT. III. THE IMPORTANCE OF PREFIXES. A. DEFINED UNITS B. DERIVED UNITS. I. ADVANTAGES OF THE METRIC SYSTEM FOR SCIENCE.

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UNDERSTANDING AND USING THE METRIC SYSTEM

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  1. UNDERSTANDING AND USING THE METRIC SYSTEM

  2. A. INTERNATIONAL STANDARDS B. EASE OF RECORDINGC. EASE OF CALCULATIONS II. UNITS OF MEASUREMENT III. THE IMPORTANCE OF PREFIXES A. DEFINED UNITS B. DERIVED UNITS I. ADVANTAGES OF THE METRIC SYSTEM FOR SCIENCE A. NANO- TO PICO- THE COMMONLY USED PREFIXES B. CONVERTING UNITS BY MOVING THE DECIMAL IV. IMAGES OF THE VERY LARGE AND VERY SMALL A. Extreme images B. THE POWERS OF TEN

  3. I. ADVANTAGES OF THE METRIC SYSTEM FOR SCIENTIFIC MEASUREMENT A. INTERNATIONAL STANDARDS B. EASE OF RECORDING C. EASE OF CALCULATIONS

  4. A. INTERNATIONAL STANDARDS… * * All metric system units are based on very specific definitions which are internationally known standards and are precisely reproducable… * Volume =1.0 liter I. ADVANTAGES OF THE METRIC SYSTEM FOR SCIENTIFIC MEASUREMENT THAT IS, MEASUREMENTS ARE THE SAME ALL OVER THE WORLD…REGARDLESS OF COUNTRY, LANGUAGE, OR DISCIPLINE… * Length =1.0 meter Mass = 1.0 kilogram

  5. B. EASE OF RECORDING MEASUREMENTS… * • All metric system units are based on TENS, that is subdivisions of the main units are based on ‘tenths’, ‘hundreths’, thousandths’, etc. I. ADVANTAGES OF THE METRIC SYSTEM FOR SCIENTIFIC MEASUREMENT .1 unit One whole unit

  6. (subdivisions can be subdivided again for more precision…but again by tenths…) .1 unit .01 unit .001 unit

  7. This means that very precise measurements can be recorded as “DECIMAL VALUES” !! .1 unit .01 unit .001 unit EXAMPLES: 2.351 liters 5.45 centimeters .802 meters 5.613 grams 9.023 meters

  8. This is a huge advantage over the older “fraction” based systems… Recording measurements is too complex, prone to errors… 1/12unit 1/16 unit 1/2unit Examples: 2 miles, 235 yards, 2 feet, 7 inches 4 gallons, 1 quart, 5 ¾ ounces 2 pounds, 8 9/32 ounce 5 yards, 2 feet, 7 1/16 inch

  9. C. EASE OF PERFORMING MATH FUNCTIONS… * • Since almost all measurements done by scientists are intended to be used in math formulas… I. ADVANTAGES OF THE METRIC SYSTEM FOR SCIENTIFIC MEASUREMENT • It is important that measurements be recorded carefully, and with as much precision as possible…. • With numbers that are easily manipulated, and/or entered into calculators…

  10. C. EASE OF PERFORMING MATH FUNCTIONS… * Examples: I. ADVANTAGES OF THE METRIC SYSTEM FOR SCIENTIFIC MEASUREMENT 1.62 kg (5.4 cm) (8.65 cm) (362 cm) Is far easier to do than… (1 lb., 9 ½ oz.) (11 ¾ in)(1 ft.4 11/16 in)(1 yd.1ft 1½ in)

  11. II.UNITS OF MEASUREMENT A. DEFINED UNITS B. DERIVED UNITS

  12. II.UNITS OF MEASUREMENT A. DEFINED UNITS THE “BASE” UNITS: SOME QUANTITIES HAVE TO BE THE STARTING POINTS… THAT IS, SOME BASIC UNITS HAVE TO BE DEFINED… #1: The unit of LENGTH: the METER– originally defined as ONE TEN-MILLIONTH the distance from NORTH POLE TO EQUATOR

  13. II.UNITS OF MEASUREMENT A. DEFINED UNITS THE “BASE” UNITS: #2 The unit of VOLUME: the LITER… defined as the space occupied by a cube measuring .1m x .1m x .1m (1 cubic decimeter—1.0 dm3) 1 DECIMETER 1 DECIMETER 1 liter = 1dm3 1 DECIMETER

  14. II.UNITS OF MEASUREMENT A. DEFINED UNITS #2 THE “BASE” UNITS: (since the cube is 1 dm x 1dm x 1dm, its volume = 1 dm3 ) (and since 1 dm = 10 cm, its volume ( 10 cm x 10 cm x 10 cm) also = 1000 cm3 ) 10 centimeters 1 liter = 1dm3 also = 1000 cm3 10 centimeters 10 centimeters

  15. II.UNITS OF MEASUREMENT A. DEFINED UNITS #2 THE “BASE” UNITS: Since the cube’s volume is 1000 cm3 , 1/1000th of its volume = 1 cm3 Using ‘prefixes’, 1/1000th of a liter = 1 millilter; then 1 cm3 = 1 ml 1 milliliter = 1 cm3

  16. II.UNITS OF MEASUREMENT A. DEFINED UNITS #3 THE “BASE” UNITS: 1.0 kilogram = mass of 1 liter of H2O The unit of MASS: the KILOGRAM… defined as the mass of 1.0 liter of pure water at 4.0oC… Since .001 L = 1 cm3, then 1 cm3 of water = .001 kg = 1.0 gr

  17. II.UNITS OF MEASUREMENT b. DERIVED UNITS UNITS THAT ARE FOUND AS THE RESULT OF CALCULATIONS… 1. The unit of DENSITY: the MASSPER VOLUME…that is, what is the mass of 1.0 cm3 (or 1.0 dm3)of a substance?

  18. To calculate DENSITY: divide the MASS by the VOLUME… If, for example, an object has a mass of 15 grams and occupies a volume of 5.0 cm3, Mass = 15 grams Volume = 5.0 cm3

  19. Divide the mass by the volume… 15 grams = 3.0 Grams/cm3 Density = 5.0 cm3 Divide numbers to get ½ of the answer Divide units to get the other ½ of the answer m = 15 g V = 5.0 cm3

  20. Divide the mass by the volume… 15 grams = 3.0 Grams/cm3 Density = 5.0 cm3 The ‘division’ slash is read as “per”… This new, more complex unit is called a ‘derived’ unit…

  21. • = “x” symbol for multiplcation When two values are multiplied, their units multiply also… (5.0 kilograms) (7.0 meters) = 35 Kgm Numeric value The ‘derived’ unit is read as “kilogram meter” or “kilogram dot meter”

  22. If two numbers which have the same units are to be multiplied… For example, (5.0 seconds) (3.0 seconds) = 15 Sec2 The ‘derived’ unit is read as “seconds squared”… Numeric value

  23. Some more complex calculations may require both mul. and div… For example, (8.0 kg) (6.0 meters) (2.0 sec) (2.0 sec) The ‘derived’ unit is read as “kilogram meter per second squared”… kgm = 12 Sec2 Numeric value

  24. Some more complex calculations may require both mul. and div… (8.0 kg) (6.0 meters) (2.0 sec) (2.0 sec) When the ‘derived’ unit is complex, it may be assigned a ‘nickname’… This unit is defined as a “NEWTON”… a unit of force. kgm = 12 Sec2 = 12 Newtons

  25. III. THE IMPORTANCE OF PREFIXES • A. FROM NANO TO PICO • B. MOVING THE DECIMAL

  26. A. FROM NANO TO PICO III. THE IMPORTANCE OF PREFIXES THE PREFIXES USED ARE COMMON TO ALL TYPES OF MEASUREMENT: EXAMPLES: microgram micrometer microliter microvolt milligram millimeter milliliter milliamp millisecond kilogram kilometer kiloliter kilojoule

  27. This prefix changes the base into a unit 1000x larger • A. FROM NANO TO PICO III. THE IMPORTANCE OF PREFIXES A prefix that makes a unit 10x larger than the base This prefix changes the base into a unit 100x larger The base of any defined or derived unit This prefix changes the base into a unit 1,000,000,000x larger GIGA 1,000,000,000 Important prefixes to know: This prefix changes the base into a unit 1,000,000x larger This prefix changes the base into a unit 1/100 as large as the base MEGA 1,000,000x This prefix changes the base into a unit 1/1000 as large as the base This prefix changes the base into a unit 1/10 as large as the base This prefix changes the base into a unit 1/1,000,000 as large as the base KILO 1000x This prefix changes the base into a unit 1/1,000,000,000 as large as the base HECTA 100x DECA 10x BASE UNIT DECI .1 CENTI .01 MILLI .001 MICRO .000 001 . NANO .000 000 001

  28. Let this entire box represent 1.0 liter… Understanding prefixes… 1/10th (.1) of the box could be called a ‘deciliter How many of these would be in 1 liter? To get those values, did you just multiply by 10? Did you do a mental short-cut and just tack on a zero? That is, just slide the decimal over and fill in with zero? in 5 liter? Did you answer 10 ? Then 50?

  29. Understanding prefixes… If the measured value gets too big (or too small), change to a more convienent unit by moving the decimal to the left or to the right, then fill in zeros… that’s really all there is to conversion!! That is the secret of converting to more convienent units within the metric system!!

  30. Understanding prefixes… Simply move the decimal 3 places to the right and fill in with zero’s (make a number 1000x bigger…) If this little box represents 1/1000th of the liter, what could it be called? What did you do to get that answer? how many of these are in the 1.0 liter? 1000? milliliter?? 1. 0 0 0 = 1000 ml

  31. GIGA 1,000,000,000 To change to a smaller unit, To change to a larger unit move the decimal to the left and fill in the zero’s MEGA 1,000,000x KILO 1000x HECTA 100x DECA 10x move the decimal to the right and fill in the zero’s BASE UNIT DECI .1 CENTI .01 MILLI .001 MICRO .000 001 NANO .000 000 001

  32. SAMPLE PROBLEM: AN ANSWER TO A CALCULATION GAVE A VALUE OF “54,500 METERS” ALTHOUGH ‘CORRECT’, THE VALUE IS LARGE AND CUMBERSOME; IT CAN BE SHORTENED AND REDUCED TO A SMALLER VALUE BY A SIMPLE CONVERSION… METERS are 1000x smaller than KILOMETERS… therefore the converted value will be 1/1000th the original! That is, move the decimal 3 places to the left!!! “54,500 METERS” can be shortened by changing the unit from ‘meters’ to ‘kilometers’

  33. GIGA 1,000,000,000 54,500 METERS = 54.5 KILOMETERS MEGA 1,000,000x KILO 1000x KILOMETER HECTA 100x DECA 10x METER BASE UNIT REMEMBER… To change to a larger unit move the decimal to the left and fill in the zero’s DECI .1 CENTI .01 MILLI .001 MICRO .000 001 NANO .000 000 001

  34. SAMPLE PROBLEM: A physics student has this value for the current in a circuit: 14.3 amps However, the formula in which she has to use the value calls for the current in MILLIAMPS… A quick conversion by moving the decimal point is easy:

  35. GIGA 1,000,000,000 To change to a smaller unit, MEGA 1,000,000x KILO 1000x move the decimal to the right and fill in the zero’s HECTA 100x DECA 10x BASE UNIT amps DECI .1 CENTI .01 milliamps MILLI .001 MICRO .000 001 NANO .000 000 001

  36. SAMPLE PROBLEM: 14.3 amps Converts to: . 14.3 , 0 0 milliamps

  37. IV. IMAGES THE VERY LARGE AND VERY SMALL-POWERS OF 10 A. THE COSMOS— astronomical images B. SUB-MICROSCOPIC-- atm imageS C. WEB SITES-POWERS OF 10

  38. A. THE COSMOS— astronomical images

  39. B. SUB-MICROSCOPIC-- atm imageS

  40. Approx. 1 micrometer (.000 001m) Image formed by an ‘ATOMIC FORCE MICROSCOPE’…

  41. Approx. 1.5 m Trenches etched onto a silicon wafer by exposure to an electron beam…

  42. Lesson Plan 1: Metric System Powers of ten animation: http://www.wordwizz.com/pwrsof10.htm http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

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