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

 Difficult to convert from one unit to another  Ex. 1 ft = 12 inches = 0.33 yard = 1/5280 miles  Customary Units  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

measurements make up all  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   

kilo - 1000

× the base

hecto deka -

100 × the base 10 × the base  Latin - fractions of 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 -

points the distance between two  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  

1 m = 100 cm

1 cm = 1/100th m

millimeter

- mm     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 

1 L = 1000 milliliters

 1 L = 1000 cubic centimeters = 1000 cm3  milliliter - mL  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  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.

    

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:

quarts.

Convert 12 gallons to units of

Unit Conversion Practice



Example:

Convert 4 ounces to kilograms.