introduction to the metric system. history created during french revolution in 1790 french king...
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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.”
Length - the distance between two pointsstandard unit is meter (m) long distances are measured in km
1km = 1000m, 1 m = 1/1000th kmSmall distances measured in cm or mm
1 m = 100 cm , 1 cm = 1/100th m1 m = 1000 mm, 1 mm = 1/1000th m10 mm = 1 cm
Measured using a meter stick or ruler
Units of Measurement
Units of Measurement
Mass - the quantity of matter in an objectstandard unit is gram (g)
Measured using a digital scale or triple beam balance
Units of Measurement
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
Units of Measurement
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.
Units of Measurement
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
Units of Measurement
Temperature - the degree of “hotness” of an object standard unit is
celsius (°C) But scientists generally
use the Kelvin Scale. Based on absolute zero.
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
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.