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 (g) measures mass
A

balance is used to measure mass.
The liter (l) measures volume which is used
when measuring liquids.
A
graduated cylinder is used to measure liquid
volume.
 Length X Width X Height is used

The meter (m) measures the length of an
object or the distance from place to place.
A

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.