MEASUREMENTS, THE
METRIC SYSTEM, AND
DENSITY
WHY DO WE USE THE METRIC
SYSTEM?
Almost all other countries are using the
metric system
 Other countries’ companies are refusing
to buy products from the U.S. if not
labeled in metric units
 Scientists need a universal way to
communicate data (SI Units)

Lets look at our system…
fractions of inch...
 12 inches to a foot….
 3 feet to a yard….
 5.5 yards to a rod an...
 320 rods to a mile...
 43,560 sq. ft. to an acre...
 16 ounces to a pound...
 12 ounces to a pound...
 4 quarts to a gallon...
 3 teaspoons to a tablespoon…

WHAT DOES THE METRIC SYSTEM
MEASURE?

The gram measures mass
A

The liter measures volume which is used when
measuring liquids.
A

graduated cylinder is used to measure volume.
The meter measures the length of an object
or the distance from place to place.
A

balance is used to measure mass.
ruler or meter stick is used to measure length.
These are the base units of measurement.
Prefixes plus base units make up the
metric system.
Staircase Conversions
Metric units  U.S. Customary Units
Practice Problems


500 mL = ___ L
600 g = ___ kg

8 ounce carton of milk = ___ mL

218 pounds = _____ kg
Density is defined as mass per unit volume. It is
a measure of how tightly packed and how heavy
the molecules are in an object. Density is the
amount of matter within a certain volume.
What is Density?
If you take the same volume of different substances, then
they will weigh different amounts.
Wood
Water
Iron
1 cm3
1 cm3
1 cm3
0.50 g
1.00 g
8.00 g
IRON
Q) Which has the greatest mass and therefore the most dense?
Density is the Mass per unit Volume
DENSITY
g/cm3
Aluminium
2.70
Iron
7.86
Brass
8.50
Wood
Slate
0.50
2.80
Glass
2.50
Lead
Marble
Wax
11.3
2.70
0.89
Density Formula
Density is mass divided by
volume.

Density
= mass/volume
The unit for mass is grams
3
The unit for volume is mL or cm


The unit for density is…
g/mL
or g/ cm3
Units for density g/cm3 or g/ml
Formula:
M = mass V= volume D = density
M=DxV
V=M/D
D=M/V
Water and Density

Since 1-gram of water has a volume of
1-mL


then the density of water =1 gram/mL.
5o-mL of water will have a mass of 50
grams
 so

again the density of water =1 g/mL.
A kg of water will have a volume of
1000-mL
 so
again the density of water =1 gram/mL.
Floating

Less dense materials
will float on top of
more dense materials.
Objects
with a density
of less than 1-g/mL will
float on top of water.
Neutral Buoyancy

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.
Objects that Sink

Objects with a density greater
than 1 g/mL will sink in water.