Nature of Science Metric System-Internati onal System of Units - - PowerPoint PPT Presentation

Nature of Science

Metric System-Internati

• nal

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

• Measurements are easily understood by all scientists
• Measurements are easier to convert than the English

system

Scientists use the SI System worldwide because:

Why use the SI 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

• ne number - 10 and a few basic units

Basic Types of Measurement

Length: measures distance between objects Mass: measures the amount of matter in an object Volume: measures the amount of space something takes up Temperature: measures molecular movement in an object

Measurement System

All Measurement systems have standards. Standards are exact quantities that everyone agrees to use as a basis of comparison.

MEASUREMENT BASIC UNIT ABBREVIATION LENGTH Meter m VOLUME Liter L TEMPERATURE Celsius °C MASS Gram g TIME Second s, sec

1 Liter 1 Meter 1 Gram

Weight vs. Mass

Measure of the force of gravity on an object Measure of amount

• f 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

Metric units

Meter

Measurement of distance

• r length

Liter

Measurement of volume

Gram

Measurement of mass

The Base Unit is the determined by the type of measurement being

• made. (mass, volume, or length)

Metric System Prefixes

The same prefixes are used regardless of the measurement type being made length, mass,

• r volume.

Kilo 1000 Hecto 100 Deca 10

Base Unit g, m , L

1 Deci .1 1/10 Centi .01 1/100 Milli .001 1/1000

Directions

• 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.

Does your paper look like this?

You must memorize the prefixes between the lines drawn.

Let’s say them together….

• Kilo-
• Hecto-
• Deka-
• (unit of measure, or meter–liter-gram)
• Deci-
• Centi-
• Milli-

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

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 units2 (m2, cm2, mm2 etc.)

Metric Measurement: Length

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 = cm3

✓ Objects without a definite length, width or height

(a rock for example), can use water displacement to determine volume. NOTE: 1 ml = 1 cm3

Metric Measurement: Temperature

Temperature is a measure of the kinetic energy

• f 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

• bject.

➢ To convert to Kelvin you add 273 degrees to

the Celsius reading.

➢ Freezing in Kelvin is 273 K, boiling is 373 K.