Measurements and the Metric System

The Metric System A universal measurement system Also called the International System or SI units Only three countries worldwide don’t use the metric system (USA, Burma, and Liberia)

The Metric System Based on multiples of ten (this makes it easy to use) Uses prefixes to identify larger or smaller units of measure Common Prefixes Symbol Multiple kilo K 1000 centi c .01 milli m .001

Metric Conversions - Length Km m dm cm mm x 1000 x 10 x 10 x 10 ÷ 1000 ÷ 10 ÷ 10 ÷10

Metric Conversions - Volume Kl l dl cl ml x 1000 x 10 x 10 x 10 ÷ 1000 ÷ 10 ÷ 10 ÷10

Metric Conversions - Mass Kg g dg cg mg x 1000 x 10 x 10 x 10 ÷ 1000 ÷ 10 ÷ 10 ÷10

Length Metric measurements A measure of linear distance Basic unit of length is the meter (m) Measurements made with a meter stick or metric ruler Metric measurements The entire meter stick represents one meter Each number represents a centimeter (there are 100 centimeters in a meter) Each little line is a millimeter (there are 1000 millimeters in a meter)

Area Metric measurements The amount of surface included within a set of boundaries Determined by measuring the length and width of an object, then multiplying Metric measurements Length = 14 cm Width = 7 cm Area = 14 cm x 7 cm = 98 cm2 (Area is always expressed in square units)

Volume Metric measurements Volume is the space that an object occupies Represents the length, width, and height of an object For solids, measurements are based on units of length (ex. cm3) and can be calculated using specific formulas Metric measurements

Calculating the volume of a rectangular prism Volume of a rectangular prism = length x width x height (l x w x h) Metric measurements Length = 10 cm Width = 3 cm Height = 4 cm Volume = l x w x h = 10 cm x 3 cm x 4 cm = 120 cm3 4 cm 3 cm 10 cm

Calculating the volume of a cylinder     Metric measurements Diameter = 10 cm 20 cm

Volume of a liquid Metric measurements A graduated cylinder is used to accurately measure the volume of liquids in milliliters Determine the volume in a graduated cylinder by reading the bottom of the meniscus at eye level Once the volume of a liquid is known, it can be converted to a “solid volume” by using the formula 1 ml = 1 cm3 Metric measurements

Mass Metric measurements Mass is a measure of the amount of matter in an object Mass is measured in grams using a balance Metric measurements The mass of an object remains the same, no matter where in the universe it is measured

Weight Metric measurements Weight is a measure of the gravitational force exerted on an object by a massive body Metric measurements Weight is measured in Newtons (N) using a spring scale Weight varies from place to place depending on the strength of the gravitational force Your weight on Earth = Mass (Kg) X 9.8 m/s² (Earth’s surface gravity) For a person with a mass of 45 Kg Weight = 45 Kg X 9.8 m/s² = 441 N

Gravity Metric measurements Gravity is the force of attraction between objects The strength of the gravitational force between objects depends on: - The distance between the objects ( the gravitational force between objects decreases with distance) -Mass ( the greater the mass of an object, the greater it’s gravitational force) Metric measurements

Density Metric measurements Density is the mass of a specific volume of an object Density is calculated by dividing the mass of an object by its volume Units for density are usually expressed in grams per cubic centimeter (g/cm3 ) Metric measurements Since the density of water is 1 g/cm3 anything with a density less than 1 g/cm3 will float in water and anything greater will sink

Calculating Density A Density = Mass Volume Volume of Object A = 5 cm x 2 cm x 3 cm = 30 cm³ Mass of Object A = 150 grams (measured on a balance) 3 cm 2 cm 5 cm Density = Mass Volume Density of Object A = 150 grams = 5 g/cm³ 30 cm³