SI Units and Measurements
The SI (système internationale) has a
base (standard) unit for every type of
measurement.
In order to be able to use SI units to
measure everything, scientists
developed a system of prefixes that
multiplies the base unit by factors of 10.
By switching the prefix, an SI unit can be
used for measurements big and small.
To convert a base unit to a smaller
unit of measurement, just move the
decimal point to the right as many
places as the difference in place
value.
When converting to a larger unit,
move the decimal point to the left as
many places as the difference in place
value.
Quantity Measured
SI Unit (symbol)
length (distance)
meter (m)
mass
kilogram (kg)
force
newton (N)
volume (capacity)
liter (L)
temperature
Kelvin (K)
time
second (s)
electric current
ampere (A )
amount of substance
mole (mol)
light intensity
candela (cd)
SI prefix (symbol)
Multiplier
Giga- (G)
1,000,000,000
Mega- (M)
1,000,000
Kilo- (k)
1,000
Hecto- (h)
100
TYPES OF MEASUREMENTS
Deca- (da)
10
Length: distance between 2 points.
Base unit
1
Weight: force exerted by a mass.
Deci- (d)
0.1
Mass: amount of matter in a liquid, solid
or gas.
Centi- (c)
0.01
Milli- (m)
0.001
Micro- (u)
0.000001
Nano- (n)
0.000000001
0.001 kilometer = 1 meter
100 centimeters = 1 meter
Volume: amount of space something
occupies.
Density: amount of matter in a volume.
Temperature: How hot or cold
something is.
Time: The period between events or
how long something lasted.
When you measure a person’s weight, you are
measuring the force they exert on the earth. Mass
and weight are NOT the same. Weight relies on
gravity (a force), but mass does not. The moon
has less gravity than Earth, objects weigh less
there. Mass is always the same, weight changes.