8th Science Metric Measurement

International System of Units Abbreviated SI Uses 10 as base unit SI Prefixes kilo hecto deca unit deci centi milli 1000 100 10 1 0.1 0.01 0.001 Larger----------------------------------- smaller (Unit – meter, liter, or gram)

Prefix staircase Kilo hecto deca unit meter deci liter centi gram milli

Length SI standard unit is meter (m) Measure with metric ruler or meter stick Know: 1 meter = 100 cm 1 cm = 10 mm 1 km = 1000 meters If measure desk use what? Why?

Mass Measure of amount of matter in object Depends on number & kind of atoms in object. Standard unit is gram. Use balance to measure mass. Mass stays the same no matter where it is measured.

Weight Measure of gravitational force which is attraction between objects 2 factors affect weight: 1) mass of objects 2) distance between objects Standard SI unit is Newton. Use spring scale to measure weight. Changes from place to place if gravity is different

Volume Measure of how much space an object occupies Volume of regular solid volume of rectangle= length x width x height V = 2m x 4m x 3m V = 24 m 3

Use graduated cylinder Unit is liter (L) or milliliter (mL) Volume of liquid Use graduated cylinder Unit is liter (L) or milliliter (mL) 1 mL = 1 cm Jar of rocks & cotton balls Which has a greater volume? same What is different? mass & weight 3

Volume of an uneven object (ex. Rock) * Use water displacement 1) Fill graduated cylinder so object will be covered ( 30 to 50 mL) 2) Gently drop object into cylinder. 3) Read new volume 4) Subtract (new volume – old volume)

Temperature Measure of how hot or cold SI unit is Kelvin absolute zero = 0 K Most scientists use Celsius 0 C = freezing point of water 100 C = boiling point of water Celsius + 273 = Kelvin Do sheet on thermometer o o o o

Density Measure of amount of matter that occupies a particular space. Formula: Density = mass/volume Problem 1: The mass of a cubic piece of metal is 80 g & its sides measure 2 cm. What is its density? mass = 80g Volume= 2cm x 2cm x 2cm = 8 cm density = 80g = 10 g/cm 8 cm 3 3 3

Problem 2: The mass of a container and pop is 700g Problem 2: The mass of a container and pop is 700g. The container by itself has a mass of 100g. The volume of pop is 200mL. What is its density? mass of pop = 700g – 100g = 600g volume = 200mL Density = 600g = 3g/mL 200mL Demo liquid density