Introduction, Scientific Method,
Measurements
Learning Objectives
• Physical Sciences
• Scientific Method
• Standard Units
• Fundamental and Derived Quantities
• Converting Units
Physical Sciences
SCIENCES
SOCIAL SCIENCES
(Latin scientia meaning knowledge)
An organized body of knowledge about the natural
Universe, and the processes by which that knowledge
Is acquired and tested
NATURAL SCIENCES
BIOLOGICAL
SCIENCES
PHYSICAL SCIENCES
PHYSICS
Concerned with the
basics principles of
matter & energy
CHEMISTRY
Deals with the
composition, structure,
and reactions of matter.
ASTRONOMY
METEOROLOGY
Study of the universe,
Study of the atmosphere,
which is the totality of
from the ground in outer
all matter, energy, space, space.
and time.
GEOLOGY
Science of the planet
Earth-its composition,
structure, processes,
and history.
Scientific Method
How can we come to understand the
Universe?
The Universe – all which is observable
The part we
(think) we
understand
The part we see
but do not
understand
Epistemology: study (or philosophy)
of knowledge.
Ways of knowing:
Fideism: acceptance of an idea,
theory, or explanation only on the
evidence of a “higher authority”.
Religious beliefs, based on faith or
revelation.
Science: a systematic method of
observation and experimentation.
Based on “evidence” and
experimental observation
Scientific revolution of
the 1600s was due
primarily to an adoption
of the scientific method
by Galileo, Newton, and
Boyle.
Scientific Method
Measurement:
a quantitative
observation
Ockham’s Razor: In
choosing between two
seemingly valid
explanations
of a particular
phenomenon, the simpler
and more general one is
preferred.
Hypothesis: a very
tentative, possible
answer or an
educated guess
Experiment: an
observation of
natural
phenomena
carried out in a
controlled
manner
Theory: a well-tested
explanation of a broad
segment of natural
phenomena
Scientific Method
• Limitations:
– Deals only with the natural world and never
invokes supernatural explanations
– Does not attempt to answer questions as the
purpose of the universe or life.
– These questions are for philosophy and
religion
Scientific Method
Beware of Pseudoscience!
Pseudoscience – the dogmatic and irrational belief in an appealing idea
that appears scientific but that is not supported by scientific methods.
* Astrology (from ancient Babylonian culture)
* UFO-ology (popular culture and mistrust of government)
* “structure –altered water” (commercial quackery)
How can you recognize a pseudoscience?
Science
Pseudoscience
The primary goal of science is to achieve a more
complete and more unified understanding of the
physical world.
Pseudosciences are more likely to be driven by
ideological, cultural, or commercial goals.
Most scientific fields are the subjects of intense
research which result in the continual expansion
of knowledge in the discipline.
The field has evolved very little since it was first
established. The small amount of research and
experimentation that is carried out is generally
done more to justify the belief than to extend it.
Observations or data that are not consistent
with current scientific understanding, once
shown to be credible, generate intense interest
among scientists and stimulate additional studies
Observations or data that are not consistent
with established beliefs tend to be ignored or
actively suppressed
Scientific explanations must be stated in clear,
unambiguous terms.
Pseudoscientific explanations tend to be vague
and ambiguous, often invoking scientific terms in
dubious contexts.
Mathematical Nature of Science
• Newton and Leibniz  Calculus
• Mathematics is the only language precise enough to
accurately describe the laws of nature.  isomorphism
• Skills needed for success in this course
– Algebra
– Basic Trigonometry
– Graphical Analysis
Do not worry about your difficulties in Mathematics.
I can assure you mine are still greater. – Albert Einstein
Measurements - Units
We need numbers in order to accurately take measurements
• When executing the scientific method we must perform experiments 
measurements  data
• Express measurements using units (i.e. metric units, English units, etc.)
Unfortunately American students must learn both systems!
• Units allow us to describe things numerically
• Measurement standards – a fixed and reproducible value for the purpose of
taking accurate measurements
How do we know the length of a meter, yard?
• Human arm, standard for length, cubit –
Egyptians
• King Loius XIV, length of the royal foot
• Distance from equator to north pole
• Modern standard, distance light,travels
in 1/299,792,458 s
The sizes of things:
What does 1025 mean?
What does 102 mean?
102 = 10  10 = 100
notice that the 2 tells us
how many zeros there are
in the answer!
10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10
 10  10  10  10  10  10  10  10 = 10,000,000,000,000,000,000,000,000
What does 10 -25 mean?
What does 10 -2 mean?
10 -2 = 0.1  0.1 = 0.01
notice that the -2 tells us
how many places to the
left we move the decimal
point!
0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1 
0.1  0.1  0.1  0.1 0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1 =
0.0000000000000000000000001
This type of notation is called “scientific notation” it is used to represent
very large and very small numbers in a manner that is efficient and easy to
do.
Units
• Mass: the kilogram
– One kilogram is the mass of a particular platinumiridium cylinder kept at the International Bureau of
Weights and Standards, Sèvres, France.
one kilogram weighs slightly less
than one kilogram
Units
• Time: the second
– One second is the time for radiation from a cesium-133 atom to
complete 9,192,631,770 oscillation cycles.
Units
• Fundamental units – fundamental because they are the
most basic quantities or properties
– Length (International System, SI  meter (m), British  foot (ft))
– Mass (SI  gram (gr), British  slug (sl))
– Time (SI & British  second (s))
• Derived units – combinations of fundamental units
– Speed (SI  m/s, British  ft/s)
– Acceleration (SI  m/s2, British  ft/s2)
– Force = mass × acceleration (SI  kg·m/s2 = Newton (N),
British  pounds (lbs)
Units
MKS : Meter-Kilogram-Second
CGS: Centimeter-Gram-Second
Derived Unit
Quantity
MKS
CGS
Area
Length2
m2
cm2
Volume
Length3
m3
cm3
Velocity
Length/Time
m/s
cm/s
Density
mass/volume =
mass/Length3
kg/m3
gr/cm3
Acceleration
Length/Time2
m/s2
cm/s2
Force
mass  Acceleration =
mass  Length/Time2
(kg  m)/s2
(gr  cm)/s2
Pressure
Force / Area =
(mass  Length/Time2)/Length2
[(kg  m)/s2]/m2
[(gr  cm)/s2]/cm2
Sometimes even the derived units are called different names because they are
so cumbersome. Typically these units are named after a scientist that contributed
to it’s origin.
Force = mass  Acceleration = (kg  m)/s2 = NEWTON
Converting Units of Measurement – Dimensional Analysis
• It is often the case that we must convert from one set of units to another.
• Suppose we want to convert 316 ft to its equivalent in meters

  0.62 mile 
1 km

 

1000 meters   1 km 
12 inches   5280 feet   2.54 cm  100 cm 

 
 
 

 1 foot   1 mile   1 inch   1 meter 
these cancel !
Example: How many kilometers is 50,000 inches?
50,000 inches
50,000
 1 foot   1 mile  1 kilometer 
12 inches   5280 feet   0.62 mile 

 
 

1x1 x1
kilometers  1.27 kilometers
12 x 5280 x 0.62
left with the units we
want !
The order that you apply the conversions makes no difference in the end!
Converting Units of Measurement – Dimensional Analysis


1 km


1000
meters


 0.62 mile 


1
km


12 inches 


1
foot


 5280 feet 


1
mile


 2.54 cm 


1
inch


 100 cm 


1
meter


If I drive 10 m/s in a school zone posted 20 miles/hour,
am I speeding? Here we must convert two things: meters to miles, and seconds
to hours
1 kilometers   0.62 miles 
10 m / s 
 1 kilometer 
1000
meters

 

 22.3 mph YES ! SLOW DOWN
 3600 sec 


1
hour


Conversions are a breeze with the metric system because it is based on powers
of 10!
Converting Units of Measurement – Dimensional Analysis
Prefix Power
Examples
Kilo-
1000, 103
Kilometer, Kiloliter, Kilogram
Hecto-
100, 102
Hectometer,Hectoliter,Hectogram
Deca-
10, 101
Decameter,Decaliter,Decagram
m, l, gr
1, 100
meter,liter,gram
Deci-
0.1, 10-1
Decimeter,Deciliter,Decigram
Centi-
0.01, 10-2
Centimeter,Centiliter,Centigram
Milli-
0.001, 10-3
Millimeter,Milliliter,Milligram
What if I had 10 milliliters and needed to convert this to kiloliters?
10 mL 
1L
1 kL

 0.00001 kL  1  10 5 kL
1000 mL 1000 L
Converting Units of Measurement – Dimensional Analysis
Prefix
Power
Examples
Kilo-
1000, 103
Kilometer, Kiloliter, Kilogram
Kind
Hecto-
100, 102
Hectometer,Hectoliter,Hectogram
Hector
Deca-
10, 101
Decameter,Decaliter,Decagram
Decked
m, l, gr
1, 100
meter,liter,gram
Mr.
Deci-
0.1, 10-1
Decimeter,Deciliter,Decigram
Deci
Centi-
0.01, 10-2
Centimeter,Centiliter,Centigram
Cinema
Milli-
0.001, 10-3
Millimeter,Milliliter,Milligram
Monday
Kind Hector Decked Mr. Deci at the Cinema on Monday.
KHDMDCM
Each word represents one of the powers of ten in the
metric system!!
Converting Units of Measurement – Dimensional Analysis
KHDMDCM
So let’s look at how this works using the example we just did.
What if I had 10 milliliters and needed to convert this to kiloliters?
KHDMDCM
10.0 mL = ?? kL
KHDMDCM
Notice that I had to move over 6 letters to get to the “K” (or Kilo). So this
corresponds to the number (and direction) of spaces I have to move my
decimal!
10.0 mL = 0.00001 kL
Let’s try another example!
Go to H-ITT Question
Converting Units of Measurement – Dimensional Analysis


1 km


1000
meters


 0.62 mile 


1
km


12 inches 


1
foot


 5280 feet 


1
mile


 2.54 cm 


1
inch


 100 cm 


1
meter


We can use converting units to solve some neat problems.
How about this. If I know that a stack of 1,000 - $1 bills is = 1 inch in height
Could I jump over $1,000,000?
Where would we start?
1,000,000 dollars


1 inch


1000
dollars


1,000,000 dollars


1 inch


1000
dollars


???
 1 ft


  83 ft
12
inches


Dimensional Analysis
• Any valid physical formula must be dimensionally
consistent – each term must have the same
dimensions
From the table:
Distance = velocity × time
Velocity = acceleration ×
time
Energy = mass × (velocity)2