Metric System Metric System
Scientific Scientific
Measurements
Measurements
Metric System Metric System
Developed by the French in the late 1700’s. Developed by the French in the late 1700’s.
Based on powers of ten, so it is very easy to Based on powers of ten, so it is very easy to use. use.
Used by almost every country in the world, Used by almost every country in the world, with the notable exception of the USA.
with the notable exception of the USA.
Especially used by scientists. Especially used by scientists.
Abbreviated SI, which is French for Systeme Abbreviated SI, which is French for Systeme International.
International.
Metric Prefixes Metric 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 = 1000 kilo = 1000
centi = 1/100 centi = 1/100 th th
milli = 1/1000 milli = 1/1000 th th
1 meter = 100 centimeters= 1000 1 meter = 100 centimeters= 1000
millimeters
millimeters
Length Length
Length is the Length is the
distance between distance between
two points.
two points.
The SI base unit The SI base unit for length is the for length is the
meter meter . .
We use rulers or We use rulers or meter sticks to meter sticks to
find the length of find the length of
objects.
objects.
Mass Mass
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 gram gram . .
A paper clip has a mass of about one gram. A paper clip has a mass of about one 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 Mass Measuring Mass
We will use a We will use a triple beam balance triple beam balance scale to scale to measure mass.
measure mass.
Gravity pulls equally on both sides of a Gravity pulls equally on both sides of a balance scale, so you will get the same balance scale, so you will get the same
mass no matter what planet you are on.
mass no matter what planet you are on.
Weight Weight
Weight is a measure of the force of Weight is a measure of the force of gravity on an object
gravity 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 are change depending on the planet you are on. on.
The SI unit for weight is the The SI unit for weight is the Newton Newton (N). (N).
The English unit for weight is the pound. The English unit for weight is the pound.
Gravity Gravity
Gravity is the force of attraction Gravity 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 weight more distance = less gravity = less weight
less distance = more gravity = more weight less distance = more gravity = more weight
more mass more mass = = more gravity more gravity = more weight = more weight
less mass less mass = = less gravity less gravity = less weight = less weight
Weight and Mass Weight and Mass
Jill Jill Earth Earth 1 1
gravity gravity
Moon Moon 1/6 1/6
ththgravity gravity
Jupiter Jupiter
2.5 2.5 graviti graviti
es es
On orbit On orbit
0 0
gravity gravity
mass mass 30kg 30kg 30kg 30kg 30kg 30kg 30kg 30kg weight
weight 300N 300N 50N 50N 750N 750N 0 0
Newton Newton
s s
Notice that Jill’s mass never changes. Her Notice that Jill’s mass never changes. Her
mother will not allow us to take parts off her, or mother will not allow us to take parts off her, or add parts to her, so her mass stays the same. Jill add parts to her, so her mass stays the same. Jill
is 30kg of little girl no matter where she goes!
is 30kg of little girl no matter where she goes!
Volume Volume
Volume is the amount of Volume is the amount of space contained in an
space contained in an object.
object.
We can find the volume We can find the volume of box shapes by the of box shapes by the
formula
formula Volume = length Volume = length x width x height
x width x height
In this case the units In this case the units would be
would be cubic cubic centimeters (cm centimeters (cm
33). ).
So a box 2 cm x 3 cm x So a box 2 cm x 3 cm x 5cm would have a volume 5cm would have a volume
of 30 cm of 30 cm
33V = L x W x H
V = L x W x H
Base Units Base Units
The base unit The base unit for volume is for volume is the the Liter Liter . .
We measure We measure volume with a volume with a
graduated graduated
cylinder
cylinder . .
Graduated Cylinders Graduated Cylinders
Liquids form curved, Liquids form curved, upper surfaces when upper surfaces when
poured into poured into
graduated cylinders graduated 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
meniscus
meniscus
Liquid Volume Liquid Volume
When the metric system was When the metric system was
created, they decided that 1 cm
created, they decided that 1 cm 3 3 of water would equal 1 milliliter of of water would equal 1 milliliter of
water and the 1 mL of water will water and the 1 mL of water will
have a mass of one gram.
have a mass of one gram.
1cm 1cm 3 3 water =1 ml of water = 1 gram water =1 ml of water = 1 gram
Water Displacement Water Displacement
We can use We can use water water displacement
displacement to find the to find the volume of objects that volume of objects that
are not boxed shaped.
are not boxed 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 Volume Water Mass and Volume
1 cm 1 cm 3 3 water = 1 mL of water = 1 water = 1 mL of water = 1 gram gram
So what would be the mass of 50 mL of So what would be the mass of 50 mL of water be?
water be?
50 grams 50 grams
So what would be the mass of 1 liter of So what would be the mass of 1 liter of water be?
water be?
1 L = 1000 mL so its mass would be 1 L = 1000 mL so its mass would be 1000 grams or a kilogram.
1000 grams or a kilogram.
Density Density
Density is the amount of matter Density is the amount of matter (mass) (mass) compared to the amount of space
compared to the amount of space (volume) (volume) the object occupies.
the object occupies.
We will measure mass in grams and We will measure mass in grams and
volume in ml or cm volume in ml or cm
33Density Formula Density Formula
Density is mass divided by volume. Density is mass divided by volume.
Density = mass/volume Density = mass/volume
Remember, all fractions are division Remember, all fractions are division problems.
problems.
Since the unit for mass is grams, and Since the unit for mass is grams, and the unit for volume is ml or cm
the unit for volume is ml or cm 3 3 , then , then
the the unit for density is g/ml, or g/ cm unit for density is g/ml, or g/ cm 3 3
Density Formula Wheel Density Formula Wheel
Formula wheels make it Formula wheels make it easy to solve density easy to solve density
problems.
problems.
Cover the property you Cover the property you are trying to find, and are trying to find, and
do what is left over.
do what is left over.
To find density, cover To find density, cover the word density. You the word density. You have mass over volume have mass over volume
remaining. So divide remaining. So divide
mass by volume to find mass by volume to find
density!
density!
Mass
density volume
Density Formula Wheel Density Formula Wheel
To find mass, you To find mass, you
cover the word mass.
cover the word mass.
You now have density You now have density
times volume remaining.
times volume remaining.
To find volume, cover To find volume, cover volume. You have mass volume. You have mass over density remaining, over density remaining,
so divide mass by so divide mass by
density to find volume density to find volume . .
Mass
density volume
Understanding Density Understanding Density
In the following illustrations, each will represent 1 In the following illustrations, each will represent 1 cm cm
33. .
Each g will represent 1 gram. Each g will represent 1 gram.
Mass = 24g Mass = 24g
Volume = 8 cm Volume = 8 cm
33
Density = 3g/cm Density = 3g/cm
33g g g g g g
g g g g g g
g g g g g g
g g g g g g g g
g g g g
g g g g g g
g g g g g g
g g
g g
g g
g g g g g g
g g g g g g
g g g g g g
g g g g g g g g
g g g g
g g g g g g
g g g g g g
g g g g g g
•In other words, there are 3 grams in
every cm cm
33. .
Density Problem 2 Density Problem 2
g g g g
g g
g g g g g g g g
g g
g g g g
g g g g
•Mass = 12 grams
•Volume = 6 cm cm
33•Density = 2 g/cm
3• In English we say the density of the object is 2
Density Problem 3 Density Problem 3
g g
g g
g g g g g g g g g g g g
g g g g
g g g g g g
g g g g g g
•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
Water and Density Water and Density
Since 1-gram of water has a volume of Since 1-gram of water has a volume of 1-mL, then the density of water will
1-mL, then the density of water will always be 1 gram/ml.
always be 1 gram/ml.
5o-mL of water will have a mass of 50 5o-mL of water will have a mass of 50
grams, so again the density of pure water grams, so again the density of pure water
will be 1 g/ml.
will be 1 g/ml.
A kg of water will have a volume of 1000- A kg of water will have a volume of 1000- mL, so it’s density will be 1 gram/ml.
mL, so it’s density will be 1 gram/ml.
Floating and Sinking Floating and Sinking
Less dense materials Less dense materials will float on top of will float on top of
more dense materials.
more dense materials.
Objects with a Objects with a
density of less than density of less than 1-g/mL will float on 1-g/mL will float on
top of water.
top of water.
Objects with a Objects with a
density greater than density greater than
1 g/mL will sink in 1 g/mL will sink in
water.
water.
Neutral Buoyancy Neutral Buoyancy
Objects with a Objects with a
density equal to the density equal to the
density of water will density of water will
float in mid water, float in mid water,
at what ever level at what ever level
you place the object.
you place the object.
Fish and submarines Fish and submarines control their depth control their depth
by changing their by changing their
density.
density.
Objects that Sink!
Objects that Sink!
Objects with a Objects with a density greater density greater
than 1 g/mL than 1 g/mL
will sink in will sink in
water.
water.
Titanic Sails the Ocean Blue Titanic Sails the Ocean Blue
The Titanic is sailing on The Titanic is sailing on its maiden voyage.
its maiden voyage.
What is the density of What is the density of this enormous, steel this enormous, steel
hulled ship, full of hulled ship, full of
machinery, coal, machinery, coal,
people, and all sorts of people, and all sorts of
heavy things?
heavy things?
It’s floating, so it’s It’s floating, so it’s density must be less density must be less
than 1 g/mL.
than 1 g/mL.
How can this be? How can this be?
The Titanic is a hollow The Titanic is a hollow vessel
vessel full of air! full of air!
Titanic verses Iceberg Titanic verses Iceberg
After HMS Titanic struck After HMS Titanic struck the iceberg, she started the iceberg, she started to fill with water.
to fill with water.
What happened to her What happened to her density?
density?
As As she took on more and she took on more and more water
more water , her density , her density got closer and closer to 1 got closer and closer to 1 g/mL.
g/mL.