Measurements and the Metric System

1. Measurements and the Metric System

2. 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)

3. The Metric System • Based on multiples of ten (this makes it easy to use) • Uses prefixes to identify larger or smaller units of measure

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

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

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

7. Length • 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)

8. Area • 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)

9. Volume • 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

10. 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

11. Calculating the volumeof a cylinder Metric measurements Diameter = 10 cm 20 cm

12. Volume of a liquid • 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

13. Mass • 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

14. Weight • Weight is a measure of the gravitational force exerted on an object by a massive body • Weight is measured in Newtons (N) using a • spring scale • Weight varies from place to place depending • on the strength of the gravitational force Metric measurements 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

15. Gravity 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

16. Density • 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

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