Metrics Pp

– Measurements

– (use metric system)

•Measuring•be precise/accurate•reliable/standardized•understood by audience

The Metric System(required in this class with a few exceptions)

--Why use the metric system?Most of the world and scientists use SI system

Metrics based on units of 10 (easy to convert)Kilo=1000

Hecto=100

Deka=10

**(meter, liter, etc)

deci=.1

centi=.01

milli=.001

Length– base unit=meter (approximately floor to

hip)– cm=width of pinky– km=12 city blocks– Instruments: tape measure, ruler, meter

stick

How long is this shell (cm/mm)?

Liquid Volume (amount of space object takes up)– base unit=liter– instrument=graduated

cylinder (eye level)-note: read bottom of meniscus

– Which has more volume?• 2 liters Pepsi or• 2 liters of air How much liquid is in this

graduated cylinder?

Solid Volume (“size” of object)– cubic meter – use ruler and formula (if regular shape)

• example: • rectangle/square is L x W x H

– use displacement (if irregular shape)– note: 1cc = 1 mL (so 5ml=5cc)– 1 mL=1/5 teaspoon

Be sure all instruments START on Be sure all instruments START on zero****zero****

Mass (amount of matter in object)

– gram (approximately a paper clip)– Family car= 1,000 kg– Instrument: balance– be sure to start on zero!!– does not change with gravity

Weight

Measure of gravitational attraction you can be “weightless” you weigh less on moon (same mass) metric unit=Newton (an apple) instrument=spring scale weight= mass x 9.8 (for Earth) ex: 90 kg person weighs 822 N

– Celsius• 100º=boiling of pure

water at sea level• 0º=freezing• room temperature about

20-25ºC– thermometer– some scientists use Kelvin

• add 273 to Celsius• 0 K=absolute zero

(motion stops)--theoretical

Temperature

Remember Mass Beam Balance grams Weight Spring Scale Newtons Temperature thermometer Deg. Celsius Length centimeters ruler Liq Volume grad cylinder mL

Solid Volume grad cylinder if irregular ruler/formula if perfect shape cubic cm Area= LxW (use ruler) units = cm2

Density Mass

Volume units: g/mL or g/cc If greater than 1, object will sink in water If less than 1, object will float in water Ex: 2.7 g/cc would ___________ in water. use

– balance– graduated cylinder (or ruler)– (calculator)

Examples Substance Density (g/cc) GOLD 19.3 LEAD 11.3 ALUMINUM 2.7 SEAWATER 1.025 PURE WATER 1.00 ICE 0.92 GASOLINE 0.7 OAK 0.7 OXYGEN 0.0014 HELIUM 0.0002

TRY THIS…

A square block of rock salt has a mass of 10.7 grams. Each edge of the block has a length of 5.0 cm. What is the density of the rock salt? (include correct units)

.0856 g/cc

Practice measuring density

Density of “rock”—in your groups …What if you have half the amount of rock? TRY THIS: Assume you are in a 25°C room with rock that has

a density of 8 g/cc. This rock glows and weighs 10 Newtons. After you carefully observe its yellow glow, you determine its mass to be 16 grams. What is the rock’s volume (include proper units)?

….. 2 cm3

More practice with density

Density lab (liquids)

Density blocks

Coke vs Diet Coke

..as time permits

Converting SI unit

– move decimal place left or

right (you are multiplying

or dividing by multiples of

10)

– like converting between

dollars and dimes

Remember King Henry

King KILO 1000 Henry HECTO 100 Died DEKA 10 Monday (m, L, g) 1 Drinking deci 1/10 (.1) Chocolate centi 1/100 (.01) Milk milli 1/1000 (.001)

Let’s try these TOGETHER…

600 millimeters = ? meters 0.35 liters = ? milliliters 1,050 grams = ? centigrams

Examples:

3.2 meters = ________ cm 320 3 mm = _____________dm .03 4.72 g = ______________kg .00472

If you want to measure the length and width of your classroom, which SI units would you use?

Which unit would you use to measure the amount of matter in your textbook?

Which would you use to measure how much water a drinking glass holds?

When would you use the Celsius scale? What is the smallest units on the metric ruler? How many mm are there in 1 cm? 1,000 meters = ________km

Metric Review

Inspiration presentation

What instrument and unit would you use to measure the following? the volume of a can of gasoline the length of your foot the mass of a vitamin tablet the density of a cube of wood

Here’s a challenge:

25 ml= ______ cubic cm Hint: 1 ml= 1 cc

so 25 ml= 25 cc

Practice measuring...

Metric Lab Stations as needed

Help available most days before school

see me to make appt.

Scientific Notation

Diameter of sun= 1,390,000,000 meters OR 1.39 x 109 meters

Diameter of one helium atom= 0.000000000244 meters

OR 2.44 x 10 -10 meters