Measurements and the Metric
System
The Metric System
• A universal measurement system
• Also called the International System or SI
units
• Only three countries worldwide don’t use
the metric system
(USA, Burma, and Liberia)
The Metric System
• Based on multiples of
ten (this makes it
easy to use)
• Uses prefixes to
identify larger or
smaller units of
measure
Common Symbol Multiple
Prefixes
kilo
K
1000
centi
c
.01
milli
m
.001
Metric Conversions - Length
x 1000
Km
÷ 1000
x 10
m
x 10
dm
÷ 10
x 10
cm
÷ 10
mm
÷10
Metric Conversions - Volume
x 1000
Kl
x 10
l
÷ 1000
x 10
dl
÷ 10
x 10
cl
÷ 10
ml
÷10
Metric Conversions - Mass
x 1000
Kg
x 10
g
÷ 1000
x 10
dg
÷ 10
x 10
cg
÷ 10
mg
÷10
Length
• A measure of linear distance
• Basic unit of length is the meter (m)
• Measurements made with a meter stick or
metric ruler
•The entire meter stick
represents one meter
•Each number represents
a centimeter (there are
100 centimeters in a meter)
•Each little line is a millimeter
(there are 1000 millimeters
in a meter)
Area
• The amount of surface included within a set of
boundaries
• Determined by measuring the length and width
of an object, then multiplying
Length = 14 cm
Width = 7 cm
Area = 14 cm x 7 cm
= 98 cm2
(Area is always expressed
in square units)
Volume
• Volume is the space that an object occupies
• Represents the length, width, and height of an
object
• For solids, measurements are based on units
of length (ex. cm3) and can be calculated using
specific formulas
Calculating the volume
of a rectangular prism
Volume of a rectangular prism = length x width x height (l x w x h)
4 cm
Length = 10 cm
Width = 3 cm
Height = 4 cm
3 cm
10 cm
Volume = l x w x h
= 10 cm x 3 cm x 4 cm
= 120 cm3
Calculating the volume
of a cylinder
Diameter = 10 cm
20 cm
Volume of a liquid
•A graduated cylinder is used to
accurately measure the volume of liquids
in milliliters
•Determine the volume in a graduated
cylinder by reading the bottom of the
meniscus at eye level
•Once the volume of a liquid is known,
it can be converted to a “solid volume” by
using the formula 1 ml = 1 cm3
Mass
•Mass is a measure of the amount of matter in an
object
•Mass is measured in grams using a balance
•The mass of an object remains the same,
no matter where in the universe it is
measured
Weight
Weight is a measure of the gravitational force
exerted on an object by a massive body
•Weight is measured in Newtons (N) using a
spring scale
•Weight varies from place to place depending
on the strength of the gravitational force
Your weight on Earth = Mass (Kg) X 9.8 m/s² (Earth’s surface gravity)
For a person with a mass of 45 Kg
Weight = 45 Kg X 9.8 m/s²
= 441 N
Gravity
Gravity is the force of attraction between objects
The strength of the gravitational force between
objects depends on:
- The distance between the objects ( the
gravitational force between objects
decreases with distance)
-Mass ( the greater the mass
of an object, the greater it’s
gravitational force)
Density
•Density is the mass of a specific volume of
an object
•Density is calculated by dividing the mass
of an object by its volume
•Units for density are usually expressed in
grams per cubic centimeter (g/cm3 )
•Since the density of water is 1 g/cm3
anything with a density less than 1 g/cm3 will
float in water and anything greater will sink
Calculating Density
3 cm
A
Volume of Object A = 5 cm x 2 cm x 3 cm
= 30 cm³
Mass of Object A = 150 grams
(measured on a balance)
2 cm
5 cm
Density = Mass
Volume
Density of Object A = 150 grams = 5 g/cm³
30 cm³