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Transcript of Created during French Revolution › in 1790‘s › 1793 French King Louis XVI beheaded ›...
Introduction to the Metric System
Measurement by design
History
Created during French Revolution› in 1790‘s› 1793 French King Louis XVI beheaded› 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 or Imperial 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
Typical 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 all around the world › Used in the scientific community and is
the only accepted form of measurement › Used by the Olympics and International
Sporting events.› Used 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 - metre mass - grams volume - litres temperature – degrees Celsius time - seconds
Advantages of Using the Metric System
There is one standard 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 - 100 × the base deka - 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 - the distance between two points› standard unit is metre (m)› long distances are measured in km
Measured using a metre stick or ruler
Prefixes and Units of Length
centimetre - cm› 1 m = 100 cm› 1 cm = 1/100th m
millimetr e- mm› 1 m = 1000 mm› 1 mm = 1/1000th m› 10 mm = 1 cm› measures very small lengths
kilometre - 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 litre (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› Litre - L
1 L = 1000 milliliters 1 L = 1000 cubic centimeters = 1000 cm3
› millilitre - mL measures small volumes 1 mL = 1 cubic centimeter 1000 mL = 1 Liter 1 mL = 1/1000th liter
› kilolitre - kL measures large volumes 1 kL = 1000 LThe SI unit for volume is NOT the litre, it is a Cubic metre.
Litre are accepted as an SI derived unit.
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
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.
Dimensional Analysis : The Rules of Unit Conversion. 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.