Metric SystemMetric System

Scientific Scientific MeasurementsMeasurements

Metric PrefixesMetric Prefixes

Regardless of the unit, the entire Regardless of the unit, the entire metric system uses the same prefixes.metric system uses the same prefixes.

Common prefixes are:Common prefixes are:

kilo = 1000kilo = 1000

centi = 1/100centi = 1/100thth

milli = 1/1000milli = 1/1000thth

1 meter = 100 centimeters= 1000 1 meter = 100 centimeters= 1000 millimetersmillimeters

LengthLength

Length is the Length is the distance distance between two between two points.points.

The SI base unit The SI base unit for length is the for length is the metermeter..

We use rulers or We use rulers or meter sticks to meter sticks to find the length of find the length of objects.objects.

MassMass Mass is the amount of matter that makes Mass is the amount of matter that makes

up an object.up an object. A golf ball and a ping pong ball are the A golf ball and a ping pong ball are the

same size, but the golf ball has a lot more same size, but the golf ball has a lot more matter in it. So the golf ball will have matter in it. So the golf ball will have more mass.more mass.

The SI unit for mass is the The SI unit for mass is the gramgram.. A paper clip has a mass of about one A paper clip has a mass of about one

gram.gram. The mass of an object will not change The mass of an object will not change

unless we add or subtract matter from it.unless we add or subtract matter from it.

Measuring MassMeasuring Mass We will use a We will use a triple beam balancetriple beam balance to to

measure mass.measure mass. Gravity pulls equally on both sides of Gravity pulls equally on both sides of

a balance scale, so you will get the a balance scale, so you will get the same mass no matter what planet you same mass no matter what planet you are on.are on.

WeightWeight

Weight is a measure of the force of Weight is a measure of the force of gravity on an objectgravity on an object..

Your weight can change depending on Your weight can change depending on the force of gravity. The gravity will the force of gravity. The gravity will change depending on the planet you change depending on the planet you are on.are on.

The SI unit for weight is the The SI unit for weight is the NewtonNewton (N).(N).

The English unit for weight is the The English unit for weight is the pound.pound.

GravityGravity

Gravity is the force of attractionGravity is the force of attraction between between any two objects with mass.any two objects with mass.

The force depends on two things:The force depends on two things: more distance = less gravity = less weightmore distance = less gravity = less weight less distance = more gravity = more less distance = more gravity = more

weightweight more massmore mass = = more gravitymore gravity = more weight = more weight less massless mass = = less gravityless gravity = less weight = less weight

Weight and MassWeight and Mass

JillJill EarthEarth

1 1 gravitygravity

MoonMoon

1/61/6thth gravitygravity

JupiterJupiter

2.5 2.5 gravitigraviti

eses

On orbitOn orbit

0 0 gravitygravity

massmass 30kg30kg 30kg30kg 30kg30kg 30kg30kg

weightweight 300N300N 50N50N 750N750N 0 0 NewtonNewton

ss Notice that Jill’s mass never changes. Notice that Jill’s mass never changes.

Her mother will not allow us to take Her mother will not allow us to take parts off her, or add parts to her, so parts off her, or add parts to her, so

her mass stays the same. Jill is 30kg of her mass stays the same. Jill is 30kg of little girl no matter where she goes!little girl no matter where she goes!

VolumeVolume Volume is the amount Volume is the amount

of space contained in of space contained in an object.an object.

We can find the We can find the volume of box shapes volume of box shapes by the formula by the formula Volume = length x Volume = length x width x heightwidth x height

In this case the units In this case the units would be would be cubic cubic centimeters (cmcentimeters (cm33).).

So a box 2 cm x 3 cm So a box 2 cm x 3 cm x 5cm would have a x 5cm would have a volume of 30 cmvolume of 30 cm33

V = L x W x HV = L x W x H

Base UnitsBase Units

The base unit The base unit for volume is for volume is the the LiterLiter..

We measure We measure volume with a volume with a graduated graduated cylindercylinder..

Graduated CylindersGraduated Cylinders

Liquids form Liquids form curved, upper curved, upper surfaces when surfaces when poured into poured into graduated cylindersgraduated cylinders

To correctly read To correctly read the volume, read the volume, read the bottom of the the bottom of the curve called the curve called the meniscusmeniscus

Liquid VolumeLiquid Volume

When the metric system was When the metric system was created, they decided that 1 created, they decided that 1 cmcm33 of water would equal 1 of water would equal 1 milliliter of water and the 1 mL milliliter of water and the 1 mL of water will have a mass of of water will have a mass of one gram.one gram.

1cm1cm3 3 water =1 ml of water = 1 water =1 ml of water = 1 gramgram

Water DisplacementWater Displacement

We can use We can use water water displacementdisplacement to find to find the volume of objects the volume of objects that are not boxed that are not boxed shaped.shaped.

We can put water in a We can put water in a graduated cylinder. If graduated cylinder. If a rock causes the level a rock causes the level to rise from 7 to 9 ml, to rise from 7 to 9 ml, the the rock must have the the rock must have a volume of 2-mL.a volume of 2-mL.

Water Mass and VolumeWater Mass and Volume

1 cm1 cm3 3 water = 1 mL of water = water = 1 mL of water = 1 gram1 gram

So what would be the mass of 50 mL So what would be the mass of 50 mL of water be?of water be?

50 grams50 grams So what would be the mass of 1 liter So what would be the mass of 1 liter

of water be?of water be? 1 L = 1000 mL so its mass would 1 L = 1000 mL so its mass would

be 1000 grams or a kilogram.be 1000 grams or a kilogram.

DensityDensity Density is the amount of matterDensity is the amount of matter

(mass) (mass) compared to the amount of compared to the amount of spacespace (volume) the object occupies. (volume) the object occupies.

We will measure mass in grams and We will measure mass in grams and volume in ml or cmvolume in ml or cm33

Density FormulaDensity Formula Density is mass divided by volume.Density is mass divided by volume. Density = mass/volumeDensity = mass/volume Remember, all fractions are Remember, all fractions are

division problems. division problems. Since the unit for mass is grams, Since the unit for mass is grams,

and the unit for volume is ml or and the unit for volume is ml or cmcm33, then the , then the unit for density is unit for density is g/ml, or g/ cmg/ml, or g/ cm33

Understanding DensityUnderstanding Density In the following illustrations, each will In the following illustrations, each will

represent 1 cmrepresent 1 cm33.. Each g will represent 1 gram.Each g will represent 1 gram. Mass = 24gMass = 24g Volume = 8 cmVolume = 8 cm33

Density = 3g/cmDensity = 3g/cm33 g gg g

ggg gg g

ggg gg g

ggg gg g

gg

g gg g

ggg gg g

ggg gg g

ggg gg g

gg

g gg g

ggg gg g

ggg gg g

ggg gg g

gg

g gg g

ggg gg g

ggg gg g

ggg gg g

gg

•In other words, there are 3 grams in every cmcm33..

Density Problem 2Density Problem 2

g gg g

g gg g g gg g

g gg g

g gg g

g gg g

•Mass = 12 grams

•Volume = 6 cmcm33

•Density = 2 g/cm3

•In English we say the density of the object is 2

grams in every cubic centimeter.

Density Problem 3Density Problem 3g g

g g g gg g

gg g gg g

g g g g gg

gg g g g g g gg g

gg

•Our previous problems were materials of uniform density. They were the same stuff throughout. But many materials are not. Gravel is a great example.

•Mass = 16 grams

•Volume = 8 mL

•Density = 2 g/mL

Objects that Sink!Objects that Sink!

Objects with Objects with a density a density greater than greater than 1 g/mL will 1 g/mL will sink in sink in water.water.