Nature of Science Metric System-Internati onal System of Units (SI)
Learning Targets: Use appropriate tools and equipment for ➢ measuring Use the metric system for measuring ➢ Use the “ladder method” and dimensional ➢ analysis to convert values between metric and English units
The Metric System ● Standardized system of measurement used by all scientists worldwide . ● Based on units of 10 ● Similar to our monetary system: 10 cents = dime 100 cents = dollar 10 dimes = dollar
Why use the SI System? Scientists use the SI System worldwide because: ● Measurements are easily understood by all scientists ● Measurements are easier to convert than the English system
The Metric System is used for everyday life in most countries except the United States, Yemen, Burma, and Brunei (Java).
In the English system you have to remember so many units numbers . . . ● 12 inches in a foot ● 3 feet in a yard ● 5,280 feet in a mile ● 16 ounces in a pound ● 4 quarts to a gallon In the SI System you only have to remember one number - 10 and a few basic units
Basic Types of Measurement Length: measures distance between objects Volume: measures the amount of space something takes up Mass: measures the amount of matter in an object Temperature: measures molecular movement in an object
Measurement System MEASUREMENT BASIC UNIT ABBREVIATION LENGTH Meter m VOLUME Liter L TEMPERATURE Celsius °C MASS Gram g TIME Second s, sec All Measurement systems have standards. Standards are exact quantities that everyone agrees to use as a basis of comparison.
1 Liter 1 Gram 1 Meter
Weight vs. Mass Measure of the force of Measure of amount gravity on an object of matter in an object NOT affected by gravity
Weight vs. Mass Weight and Mass are related, but NOT the same. ➢ Weight can change depending on location ➢ Mass is constant regardless of location ➢ The greater the mass, the larger the pull of gravity. The larger the pull of gravity, the greater the weight
Mass Vs. Weight Activity
Metric Base Units The Base Unit is the determined by the type of measurement being made. (mass, volume, or length) Metric units Meter Liter Gram Measurement of distance or length Measurement of volume Measurement of mass
Metric System Prefixes Kilo 1000 The same prefixes are used Hecto 100 regardless of the measurement Deca 10 type being made length, mass, or volume. Base Unit 1 g, m , L Deci .1 1/10 Centi .01 1/100 Milli .001 1/1000
● Pass out a handout and a ruler. ● Write your name in the upper right corner. ● Locate the column of prefixes. ● Draw a line above kilo- all the way across the page – edge to edge. ● Draw another line below milli- all the way across the paper – edge to edge. Directions
Does your paper look like this?
You must memorize the prefixes between the lines drawn.
● Kilo- ● Hecto- ● Deka- ● (unit of measure, or meter–liter-gram) ● Deci- ● Centi- ● Milli- Let’s say them together….
Practice Abbrev. Word Meaning mm millimeter one thousandth meter cg kL cm mL mg km kg
Abbrev. Word Meaning mm millimeter .001 meter (thousandth) cg centigram .01 gram (hundredth) kL kiloliter 1000 liters cm centimeter .01 meter (hundredth) mL milliliter .001 meter (thousandth) mg milligram .001 gram (thousandth) km kilometer 1000 meters kg kilogram 1000 grams
“Ladder Method” • Used for metric to metric conversions • Conversions are done by moving the decimal point. • Larger to smaller unit: Move decimal point to the right • Smaller to larger unit: Move decimal point to the left
Let’s practice … Take out a piece of scratch paper and write this problem down: • 3.4m = _________ cm • Put your pencil on the decimal (.) • Put your finger on (units) where m would be. • Move your finger right 2 times to cm. • Move the decimal right 2 times.
Did you get this answer … • 3.4m = 340 cm • Great! • Let’s try another. • 500mg = _______ g • Use the same procedure. Put your pencil on the decimal and your finger on the corresponding space and move.
Ready … Set … Move … . • 500mg = _____g • Put your pencil where the decimal should be and your finger on the mg box. • Move your finger 3 times left then move the decimal 3 times left. • Did you get … • 500mg = .5g • Good job!
One more time … • .2kL = ______ L • Pencil on the decimal and finger on the chart. • Count 3 right then move the decimal 3 right. • Did you get … • .2kL = 200L • Yea!
That was easy … • Practice just a few then check your answers with a partner. • 3.5 cm = _____mm • 500 mg = _____g • 2L = _____mL • .25km = _____m
Check your answers Did you get … • 3.5 cm = 35 mm • 500mg = .5g • 2L = 2000mL • .25km = 250m • Now all you have to do is practice, practice, practice … .
Metric Conversion Challenge ** Pass Out Handout **
Things to Remember ■ All measurements need a number and a unit! ■ Basic units of Measurement (meter, liter, gram) ■ Metric prefixes
Metric Measurement: Length Length is the distance between two points. Does not matter if it is width, height, depth, etc. ✓ All are length measurements. The basic unit of length in the SI System is the ✓ meter. The meter is about the length of the English yard ✓ (3 feet). Area is a variation of a length measurement. ✓ Area is length x width. ➢ Expressed in units 2 (m 2 , cm 2 , mm 2 etc.) ➢
Metric Measurement: Mass Mass is a measurement of the amount of matter in an object. ✓ Basic unit of mass is the gram. There are 454 grams in one pound. ✓ Weight and mass are related, but NOT the same. ➢ Weight is the pull of gravity on an object ➢ The greater the mass, the larger the pull of gravity.
Metric Measurement: Volume Volume is a measurement of the amount of space something takes up. ✓ The basic unit used for volume is the liter. This unit is used for the volumes of liquids. ✓ Volumes of solids are figured using this formula: (L)ength x (W)idth x (H)eight cm x cm x cm = cm 3 ✓ Objects without a definite length, width or height (a rock for example), can use water displacement to determine volume. NOTE: 1 ml = 1 cm 3
Metric Measurement: Temperature Temperature is a measure of the kinetic energy of the atoms in an object. ✓ Temperature is measured with a thermometer and measured in Celsius or Kelvin. ✓ Celsius ranges from 0 (freezing) to 100 (boiling). ✓ The Kelvin scale begins at absolute zero, or 0 K. At 0 Kelvin no more heat can be removed from an object. ➢ To convert to Kelvin you add 273 degrees to the Celsius reading. ➢ Freezing in Kelvin is 273 K, boiling is 373 K.
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