Introduction to the Metric System

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

Advantages of Using the Metric System • 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 • Simple to use • A few base unitsmake 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 toconvert 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 meter(m) • long distances are measured in km • Measured using a meter stick or ruler

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

Prefixes and Units of Volume • 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

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 canwith 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 ACS Ms. Grogan

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.

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.

Introduction to the Metric System