Introduction to the Metric System Measurement by design

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 = 1/100 th m � millimetr e- mm › › � 1 m = 1000 mm 1 mm = 1/1000 th m 10 mm = 1 cm measures very small lengths kilometre - km › 1 km = 1000 m › 1 m = 1/1000 th 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 cm 3 = 1 dm 3 › Measured using a graduated cylinder � Capacity container - a measure of the volume inside a

Prefixes and Units of Volume › Litre - L � 1 L = 1000 milliliters � 1 L = 1000 cubic centimeters = 1000 cm 3 › millilitre - m. L �measures small volumes � 1 m. L = 1 cubic centimeter � 1000 m. L = 1 Liter � 1 m. L = 1/1000 th liter › kilolitre - k. L �measures large volumes � 1 k. L = 1000 L The SI unit for volume is NOT the litre, it is a Cubic metre. Litre 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 l Displacement l 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 cm 3 › 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/m. L �g/cm 3 �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.