LECTURE 1
INTRODUCTION TO PHYSICS
Instructor: Kazumi Tolich
Lecture 1
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Reading chapter 1-1 and 1-2
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Scientific method
The SI units
Scientific notation
What are science and physics?
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Science is observing, discovering, understanding,
and recording the natural world.
¨  A knowledge of science tells us what is possible in
nature.
¨  Physics is the study of the general principles of the
universal phenomena.
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Why do we learn science?
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To expand awareness of the universe
¨  To understand problems of modern society and their
solutions
¨  To understand everyday technology
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Importance of mathematics
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When the idea of science is expressed in
mathematical terms, they are unambiguous.
¨  Mathematics do not have double meanings to
confuse you.
¨  When findings in nature are expressed
mathematically, they are easier to verify or
disprove by experiments.
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Theories, models, and laws
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We formulate models, theories, and laws based on analyzed data to generalize
and communicate experimental results.
A theory is a synthesis of a large body of information that encompasses well-tested
and verified hypothesis about certain aspects of the natural world.
A model is a representation of something that is often too difficult to display
directly and is only accurate under limited situations. Some theories include models
to help visualize phenomena.
A law uses concise language to describe a generalized pattern in nature. Often
laws are parts of a theory.
A principle is a less broadly applicable statement.
Scientific method
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Scientific method is a careful application of
experience and reason to answer questions.
¨  Scientific process was introduced in the 16th century
by Galileo and others.
¨  Scientific method is effective in gaining, organizing,
and applying new knowledge.
¨  It often consists of 5 steps.
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Scientific process steps 1 & 2
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The first step in scientific method is to recognize the
problem.
¨  The second step is to form a hypothesis.
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¤  A
hypothesis is an educated suggestion or guess that is
experimentally verifiable.
¤  If an idea does not yield any experimentally verifiable
consequences, it is not a scientific hypothesis.
Scientific process steps 3 & 4
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The third step is to predict the consequences of the
hypothesis.
¨  The fourth step is to perform experiments to test the
predictions.
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the experiment disagrees with the predictions, we must go
back to step 2 and come up with a new hypothesis.
Scientific process step 5
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The fifth step is to formulate the simplest rule
that organizes hypothesis, prediction, and
experimental outcome into a theory.
Scientific method summary
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1. 
2. 
3. 
4. 
5. 
Recognize a problem.
Make a hypothesis.
Predict the consequences of the hypothesis.
Perform experiments to test predictions.
Formulate a theory.
Scientific theory
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Can a scientific theory be proven to be certainly
true?
¨  Can a scientific theory be proven to be wrong?
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Scientific method example
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Problem:
The number of measured electron-type-neutrinos from the sun did not match
the expectation from nuclear fusion model, which produce electron-typeneutrinos.
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Hypothesis:
As they travel, neutrinos changed their type into two other types so that they
cannot be detected.
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Prediction:
An experiment measuring neutrinos from other sources should also see the
mismatch.
Theory through scientific method
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Experiment:
The KamLAND experiment measured
less electron-type-neutrinos from
nuclear reactors than expected.
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Theory:
“Neutrino Oscillation,” changing of
neutrino types while neutrinos are
traveling, was established.
Units
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A unit is a standard, relative to which a quantity such as length
is measured.
Examples of units are inches, pounds, degrees, etc.
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If you want to tell someone the distance from your house to school, you
never just say “0.5,” but say “0.5 miles” with units to avoid confusions.
Importance of having units:
https://en.wikipedia.org/wiki/Mars_Climate_Orbiter
https://www.youtube.com/watch?v=zN9LZ3ojnxY
Base quantities and the SI units
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In 1960, an international committee established
a set of standards, the SI units.
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Length in meters (m)
Mass in kilograms (kg)
Time in seconds (s)
Electric current in amperes (A)
Temperature in kelvin (K)
Amount of substance in moles (mol)
Luminosity in candela (cd)
Countries that do not
use the SI units.
All the other units can be expressed as a combination of the base SI units.
Demo 1
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Basic SI units
¤  Demonstration
of 1kg, 1m, and 1s.
Length
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Length is a distance between two points.
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History of the definition of the meter:
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In 1791, one ten-millionth of the distance between the equator to
the North Pole along the line that goes through Paris.
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In 1889, the distance between two lines on a platinum-iridium bar
stored in France.
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By 1960, 1650763.73 wavelengths of orange red-light from
krypton-86.
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In 1983, the distance traveled by light in vacuum in
1/299792458 seconds.
Mass
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Mass is the quantitative measure of
inertia.
In 1887, the kilogram was defined as
being equal to the mass of the
International Prototype Kilogram (a
platinum-iridium alloy), stored in France.
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1kg is close to the mass of one liter of water.
Time
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¨ 
History of the definition of the second:
¤  Before
1967, 1/86400 of the mean solar day.
¤  In 1967, 9192631770 times the period of vibration of
radiation from the cesium-133 atom.
Scientific notation
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¨ 
Power of 10:
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1000 = 10 x 10 x 10 = 103
0.01 = 1 / 10 / 10 = 10-2
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1 = 100
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Multiplication and Division:
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In multiplication, the exponents are added:
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102 x 103 = 105
In division, the exponents are subtracted:
102 / 103 = 10-1
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In scientific nation, a number is written as a product of a number between 1 (inclusive) and 10 (exclusive)
times a power of 10.
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3500 is 3.5 x 103
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0.035 is 3.5 x 10-2
Prefixes for power of ten
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