Introduction to the Metric
System
ACS
Ms. Grogan
History

Created during French Revolution
in 1790
 French King overthrown
 National Assembly of France sets up new
government
 French Academy of Science told to design
new system of weights and measures
 Lavaiosie appointed to head committee

History

Called Systeme International d’Unitès,


or SI - International System of Units
Revised periodically

by International Bureau of Weight and
Measures
Customary Units of Measurement

The English System

a collection of functionally unrelated units


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Difficult to convert from one unit to another
Ex. 1 ft = 12 inches = 0.33 yard = 1/5280 miles
Customary Units

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length - inch, foot, yard, mile
weight/mass - ounce, pound
volume - teaspoon, cup, quart, gallon
temperature - degrees Fahrenheit
time - minutes, hours
Advantages of Using the Metric
System

Universal - used everywhere
by all scientists to communicate
 by all industrialized nations

except United States
 U.S. loses billions of dollars in trade

Advantages of Using the Metric
System

Simple to use

A few base units make up all
measurements
length - meter
 mass - grams
 volume - liters
 temperature – degrees Celsius
 time - seconds

Advantages of Using the Metric
System

There is only one unit of measurement for
each type of quantity

To simplify things, very small and very large
numbers are expressed as multiples of the base
unit.


Prefixes are used to represent how much smaller or larger
the quantity is compared to the base unit.
Easy to convert from one unit to another


shift decimal point right
shift decimal point left
Advantages of Using the Metric
System

Same set of prefixes for all units

Greek - multiples of the base



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Latin - fractions of the base

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kilo - 1000 × the base
hecto - 100 × the base
deka - 10 × the base
deci - tenths of the base
centi - hundredths of the base
milli - thousandths of the base
Mnemonic: “Kids Have Dropped Over Dead
Converting Metrics.”
Metric Prefixes
Units of Length

Length - the distance between two
points
standard unit is meter (m)
 long distances are measured in km


Measured using a meter stick or ruler
Prefixes and Units of Length

centimeter - cm

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millimeter - mm
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1 m = 100 cm
1 cm = 1/100th m
1 m = 1000 mm
1 mm = 1/1000th m
10 mm = 1 cm
measures very small lengths
kilometer - km



1 km = 1000 m
1 m = 1/1000th km
measures long distances
Measuring Mass

Mass - the quantity of matter in an object


standard unit is gram (g)
Measured using a digital scale or triple
beam balance
Measuring Volume and Capacity

Volume - the amount of space occupied
by an object
standard unit is liter (L)
 1 L = 1000 ml = 1000 cm3 = 1 dm3
 Measured using a graduated cylinder


Capacity - a measure of the volume
inside a container
Prefixes and Units of Volume

Liter - L
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milliliter - mL
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1 L = 1000 milliliters
1 L = 1000 cubic centimeters = 1000 cm3
measures small volumes
1 mL = 1 cubic centimeter
1000 mL = 1 Liter
1 mL = 1/1000th liter
kiloliter - kL


measures large volumes
1 kL = 1000 L
Measuring Volume

Measured with a graduated
cylinder


Determine value of each
mark on the scale
Read scale using the lowest
position of the meniscus


Measure the meniscus at
eye level from the center of
the meniscus.
In the case of water and
most liquids, the meniscus
is concave. Mercury
produces a convex
meniscus.
Displacement

Displacement
Amount of water an object replaces
 Equal to its volume

Volume of a Solid, Irregular Object

Displacement - amount of
water an object replaces

Procedure

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Place graduate beaker beneath
spout
Fill the overflow can with water
until water begins to spill
Empty the excess water
Place object to be measured into
the overflow can
Remove when water stops flowing
out of the can
Measure the displaced water
using a graduated cylinder.
Volume of a Solid, Irregular Object

Displacement

Calculate the
difference
between the
initial and final
volume
measurement.
Volume of a Solid, Regular Object

Volume - length x width x height



V = 2.8 cm x 3.2 cm x 2.5 cm
V = 22.4 cm3
Measured with a ruler
Calculating Density

Density - a specific property of matter that is
related to its mass divided by the volume.


D=M/V
the ratio of mass to volume


used to characterize a substance
each substance has a unique density

Units for density include:



g/mL
g/cm3
g/cc
Measuring Time

Time

metric unit is second (s)
Measuring Temperature

Temperature the degree of
“hotness” of an
object


standard unit is
celsius (°C)
measured with
a
thermometer
Temperature Conversions

Conversion Between
Fahrenheit, Celsius, and
Kelvin
 Example:


Convert 75 ºC to ºF
Convert -10 ºF to ºC
Measurement Unit Conversion

You can convert between units of
measurement
within the metric system
 between the English system and metric
system

Conversion and the Metric
System
ACS
Ms. Grogan
Measurement Unit Conversion

You can convert between units of
measurement
within the metric system
 between the English system and metric
system

Unit Conversion

Let your units do the work for
you by simply memorizing
connections between units.

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Example: How many donuts
are in one dozen?
We say: “Twelve donuts in a
dozen.”
Or: 12 donuts = 1 dozen
donuts
What does any number
divided by itself equal?
ONE!
Unit Conversion

This fraction is called a unit
factor


Multiplication by a unit
factor does not change the
amount - only the unit.
Example: How many
donuts are in 3.5 dozen?

You can probably do this in
your head but try it using the
Factor-Label Method.
Unit Conversion Rules
Start with the given information…
 Then set up your unit factor…
 See that the original unit cancels out…
 Then multiply and divide all numbers…

Unit Conversion Practice

Example: Convert 12 gallons to units of
quarts.
Unit Conversion Practice

Example: Convert 4 ounces to kilograms.