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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
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
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
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
Length - the distance between two pointsstandard 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 objectstandard 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 objectstandard unit is liter (L)1 L = 1000 ml = 1000 cm3 = 1 dm3Measured 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
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
DisplacementAmount of water an object replacesEqual 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
Timemetric 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 measurementwithin the metric systembetween the English system and metric
system
Conversion and the Metric System
ACS
Ms. Grogan
Measurement Unit Conversion
You can convert between units of measurementwithin the metric systembetween 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: Convert 12 gallons to units of quarts.
Unit Conversion Practice
Example: Convert 4 ounces to kilograms.
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