Unformatted text preview: Metric System
copyright cmassengale Metric System
Metric Developed by the French in the late 1700’s.
Based on powers of ten, so it is very easy to use.
Used by almost every country in the world, with the notable exception of the USA.
Especially used by scientists.
Abbreviated SI, which is French for Systeme International. copyright cmassengale Metric Prefixes
Regardless of the unit, the entire metric system uses the same prefixes. Common prefixes are:
kilo = 1000
centi = 1/100th
milli = 1/1000th
1 meter = 100 centimeters= 1000 millimeters copyright cmassengale Length
Length Length is the
The SI base unit
for length is the
We use rulers or
meter sticks to
find the length of
copyright cmassengale Mass
Mass Mass is the amount of matter that
makes up an object.
A golf ball and a ping pong ball are the
same size, but the golf ball has a lot
more matter in it. So the golf ball will
have more mass.
The SI unit for mass is the gram.
A paper clip has a mass of about one
The mass of an object will not change
unless we add or subtract matter from
copyright cmassengale Measuring Mass
Measuring We will use a triple beam balance scale to
Gravity pulls equally on both sides of a
balance scale, so you will get the same mass
no matter what planet you are on.
no copyright cmassengale Weight
Weight Weight is a measure of the force of gravity on an object.
Your weight can change depending on the force of gravity. The gravity will change depending on the planet you are on.
The SI unit for weight is the Newton (N).
The English unit for weight is the pound. copyright cmassengale Gravity
Gravity Gravity is the force of attraction between any two objects with mass.
The force depends on two things:
more distance = less gravity = less weight
less distance = more gravity = more weight
more mass = more gravity = more weight
less mass = less gravity = less weight
copyright cmassengale Weight and Mass
Jill Earth Moon Jupiter On orbit 1 gravity 2.5 gravities
30kg 0 gravity 750N 0 Newtons mass 30kg 1/6th gravity
30kg weight 300N 50N 30kg Notice that Jill’s mass never changes. Her mother will not allow us to take parts off her, or add parts to her, so her mass stays the same. Jill is 30kg of little girl no matter where she goes! copyright cmassengale Volume
Volume Volume is the amount
of space contained in
We can find the volume
of box shapes by the
formula Volume =
length x width x height
In this case the units
would be cubic
So a box 2 cm x 3 cm x
5cm would have a
volume of 30 cm3
copyright cmassengale V=LxWxH Base Units
The base unit for volume is the Liter. We measure volume with a graduated cylinder. copyright cmassengale Graduated Cylinders
Liquids form curved,
upper surfaces when
graduated To correctly read the
volume, read the
bottom of the curve
called the meniscus
meniscus copyright cmassengale Liquid Volume
When the metric system was created,
they decided that 1 cm3 of water
would equal 1 milliliter of water and
the 1 mL of water will have a mass of
one 1cm3 water =1 ml of water = 1 gram
water copyright cmassengale Water Displacement
Water We can use water
displacement to find the
volume of objects that
are not boxed shaped.
We can put water in a
graduated cylinder. If a
rock causes the level to
rise from 7 to 9 ml, the
the rock must have a
volume of 2-mL.
copyright cmassengale Water Mass and Volume
Water 1 cm3 water = 1 mL of water = 1 gram
So what would be the mass of 50 mL of water be?
So what would be the mass of 1 liter of water be?
1 L = 1000 mL so its mass would be
1000 grams or a kilogram.
1000 copyright cmassengale Density
Density Density is the amount of matter (mass)
compared to the amount of space (volume)
the object occupies.
We will measure mass in grams and
volume in ml or cm3
volume copyright cmassengale Density Formula
Density is mass divided by volume. Density = mass/volume Remember, all fractions are division problems. Since the unit for mass is grams, and the unit for volume is ml or cm3, then the unit for density is g/ml, or g/ cm3 copyright cmassengale Density Formula Wheel
Density Formula wheels make it
easy to solve density
Cover the property you
are trying to find, and
do what is left over.
To find density, cover
the word density. You
have mass over volume
remaining. So divide
mass by volume to find
copyright cmassengale Mass
density volume Density Formula Wheel
Density To find mass, you cover
the word mass. You
now have density times
To find volume, cover
volume. You have
mass over density
remaining, so divide
mass by density to find
volume copyright cmassengale Mass
density volume Understanding Density
Understanding In the following illustrations, each will represent 1 cm3.
Each g will represent 1 gram.
Mass = 24g
Volume = 8 cm3
Density = 3g/cm3
g g g
g g g
g g g
g g g
g g g g g g copyright cmassengale 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 cm3. copyright cmassengale Density Problem 2
g g g g g g g g g g g g •Mass = 12 grams
•Volume = 6 cm3
•Density = 2 g/cm3 •In English we say the density of the object is 2 grams in every cubic centimeter. copyright cmassengale Density Problem 3
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
•Density = 2 g/mL
copyright cmassengale Water and Density
Water Since 1-gram of water has a volume of
1-mL, then the density of water will
always be 1 gram/ml.
5omL of water will have a mass of 50 grams, so again the density of pure water will be 1 g/ml.
A kg of water will have a volume of 1000mL, so it’s density will be 1 gram/ml. copyright cmassengale Floating and Sinking
Floating Less dense
materials will float
on top of more
Objects with a
density of less than
1-g/mL will float on
top of water.
Objects with a
density greater than
1 g/mL will sink in
copyright cmassengale Neutral Buoyancy
Neutral Objects with a density equal to the density of water will float in mid water, at what ever level you place the object.
Fish and submarines control their depth by changing their density. copyright cmassengale Objects that Sink!
Objects Objects with a
than 1 g/mL will
sink in water.
sink copyright cmassengale Titanic Sails the Ocean Blue
Titanic The Titanic is sailing on
its maiden voyage.
What is the density of
this enormous, steel
hulled ship, full of
people, and all sorts of
It’s floating, so it’s
density must be less
than 1 g/mL.
How can this be?
The Titanic is a hollow
vessel full of air!
copyright cmassengale Titanic verses Iceberg
Titanic After HMS Titanic
struck the iceberg, she
started to fill with water.
What happened to her
As she took on more
and more water, her
density got closer and
closer to 1 g/mL.
The denser the ship
became, the lower she
settled into the water.
copyright cmassengale Wreck of the Titanic
Wreck What is the density
of the Titanic resting
on the ocean floor?
Must be greater than
1 g/mL, as her steel
hull is full of water
instead of air.
instead copyright cmassengale Comparing Densities
object? copyright cmassengale Density Review
Density We don’t actually count g’s to find the mass of objects. How would you find the mass of a rock?
Use a balance scale.
In real life, how would you find the volume of a rock?
Use a graduated cylinder and see how much water the rock displaces. copyright cmassengale copyright cmassengale ...
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- Winter '11
- International System of Units, Kilogram, copyright cmassengale, Density Review