Units of Measurement
THE SI SYSTEM AND UNITS OF MEASUREMENT
MEASUREMENT
Measurement is used to measure quantities.
 Quantity is something that has magnitude, size,
or amount (volume).
 A quantity is not the same as a measurement.

SI SYSTEM OF MEASUREMENT
In the late 18th century, scientists used the
metric system. The metric system is a
forerunner to the SI System.
 Scientists all over the world use a single
measurement system called Le Systeme
International d’Units, abbreviated SI.


It was adopted in 1960 and has both base
units and derived units.
SI BASE UNITS

The most common base units that we will study
include:
Quantity
Quantity
Symbol
Unit name
Unit
abbreviation
Length
l
meter
m
Mass
m
kilogram
kg
Time
t
second
s
Temperature
T
Kelvin
K
LENGTH
The SI standard unit for length is the meter.
 A distance of 1m is about the width of an average
doorway.
 To express longer distances, the kilometer (km) is
used. One kilometer is equal to 1000 m.
 To express shorter distances, the centimeter (cm)
is used. One centimeter is equal to 1/100 of a
meter.
 Length can be measured using a meter stick or
rulers.

MASS



Mass is a measure of the quantity of matter. The
standard unit for mass is the kilogram (kg).
The gram (g), which is 1/1000 of a kg is used for
measuring masses of small objects such as flasks and
beakers. Mass is typically measured using a balance.
Mass is different from weight. Weight is a measure of
the gravitational pull on matter. The weight of an object
increases as gravity acts on it. The weight of an object
on the moon is about 1/6th of its weight on Earth. So, a
human on Earth who weighed 126 lbs. would weight
how much on the moon?
TIME
The standard unit of measurement for time is the
second (s).
 Time can be measured using stop watches, clocks,
count down timers, and other time pieces.
 Larger amounts of time are measured in minutes
and hours.
 There are 60 seconds in one minute. There are 60
minutes in one hour. Given that there are 24 hours
in one day, how many seconds are there in one
day?

TEMPERATURE
The standard unit of measurement for
temperature is degrees Kelvin (K).
 Temperature can also be measured in degrees
Celsius (°C) and degrees Fahrenheit (°F).
 To convert degrees Celsius (°C) to degrees
Fahrenheit (°F) multiply by 1.8 and then add 32.
To convert degrees Fahrenheit to degrees Celsius,
subtract 32 and then divide by 1.8
 ° K= °C + 273
 Temperature is measured using a thermometer.
(measures the degree of heat or coolness)

DERIVED UNITS

Derived units are combinations of base units.
They are produced by multiplying or dividing
standard units. The derived units we will study
include:
Quantity
Area
Volume
Quantity
symbol
Unit
Unit
abbreviati
on
A
square
meter
m2
V
cubic
meter
m3
kilograms
AREA
Area is length times the width. It is expressed
as square meters.
 Area can also be expressed as cubic
centimeters.
 What is the area of a rectangle that has an a
length of 6 cm and a width of 16 cm?

16 cm


1
11111cmam
6 cm
VOLUME
Volume is the amount of space occupied by an
object. The derived SI unit for volume is cubic
meters. The cubic meter is rather large, so a more
common unit of cubic centimeters is more
commonly used.
 Non-SI units are also used to measure volume
such as the milliliter (mL) and the liter (L), which is
1000 cm3. There are 1000 mL in 1 L.
 Beakers, flasks, and graduated cylinders are often
used to determine the volume of liquids.

DENSITY
Density is the ratio of mass to volume, or mass
divided by volume. It can be written:
density=mass/volume or D=m/V
Density is a characteristic physical property of a
substance that does not depend on the size of
the sample. As the mass of an object
increases, its volume increases.
* Question: Are raisins, more or less dense than
soda water? Let’s see!

Name
Volume (cm^3)
Mass (kg)
Michael
120384
85
John
Colleen
77509
59
35000
56
Fabrizio
Abella
135456
47824
80
Aaron
174096
101
Felicita
95700
63
Travis
89775
102
Franklin
97559
70
Steven
90580
70
Kayla
90180
65
Nicholas
Brianna
89280
66
100200
70
62
Name
Volume = “X”
Mass = “Y”
Oscar
109620 cm^3
74kg
0.000235
Crystal
69,900 cm^3
51kg
0.0002857
Ron
172,900 cm^3
79kg
0.000222
Brian
170280 cm^3
74kg
0.0002
Chevon
126412 cm^3
65kg
0.000211
Amber
94350 cm^3
Maria
56160cm^3
Danielle
115520 cm^3
Robert
0.0002
49kg
0.0002
131760cm^3
60kg
0.00021
Emmanuel
129960 cm^3
62kg
0.000192
Brittany
95456 cm^3
55kg
0.00027
Alyssa
110160 cm^3
Jaclynne
65490 cm^3
50kg
0.0003
Jake
142740 cm^3
67kg
0.0003
0.00027