Lecture 2 Introduction to the Metric System.ppt

Introduction to the Metric
System

History
Created during French Revolution
in 1790
National Assembly of France sets up new
government
French Academy of Science told to design
new system of weights and measures

History
Called System 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
 length : inch, foot(ft), yard(yd), mile(mi)
 Ex. 1 ft = 12 inches = 0.33 yard = 1/5280 miles
 weight/mass : ounce(oz), pound(lb), ton.
 volume : pint, cup, quart(qt), gallon(gall).
 temperature : degrees Fahrenheit
 time : minutes, hours

Universal
 used everywhere
by all scientists to communicate
by all industrialized nations
Advantages of Using the Metric
System

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

Each of the base units in the metric system can be
modified with different prefixes which multiply out the
base unit by some factor
Prefix Symbol Meaning
 Giga G 1,000,000,000 times the base unit
 Mega M 1,000,000 times the base unit
 Kilo k 1,000 times the base unit
 Hecto h 100 times the base unit
 Deka da 10 times the base unit
 Deci d 0.1 of the base unit
 Centi c 0.01 of the base unit
 Milli m 0.001 of the base unit
 Micro  0.000001 of the base unit
 Nano n 0.000000001 of the base unit

Length - the distance between two
points
standard unit is meter (m)
long distances are measured in km
Measured using a meter stick or ruler
Units of Length

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

 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
Prefixes and Units of Volume

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

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(For liquid and solids)
 g/cm3(For liquid and solids)
 g/L(for gases)

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

A. Scientific
Notation
Very large or very small numbers can be expressed
using scientific notation
 The number is written as a number between 1 and 10
multiplied by 10 raised to a power.
e.g. 7200 is 7.2 x 103
 The power of 10 depends on:
 The number of places the decimal point is moved.
 The direction the decimal point is moved.
Left  Positive exponent
Right  Negative exponent

A. Scientific Notation
Representing Large Numbers
93,000,000 miles from the Earth to the
Sun (sunlight takes 8 minutes to reach
us)
93,000,000 = 9.3 x 10,000,000
= 9.3 x 10 x 10 x 10 x 10 x 10 x 10 x 10
= 9.3 x 107 (Decimal point moved 7 digits to the left)
Number between 1 and
10
Appropriate power of
ten

A. Scientific Notation
• Representing Small Numbers
0.000167
To obtain a number between 1 and 10 we must move the
decimal point to the right.
0.000167 = 1.67 10-4
10-4
= 1/10000 (one ten-thousandth)

Unit Conversion Practice
 Example: Convert 12 gallons to units of
quarts.

Unit Conversion Practice
 Example: Convert 4 ounces to kilograms.

Lecture 2 Introduction to the Metric System.ppt

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Lecture 2 Introduction to the Metric System.ppt