PHY081 Physics (Semester I)

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PHY093
Physics 1
Introduction
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Physics (Giancoli)
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The most basic of the sciences
Deals with behavior and structure of matter
Usually divided into
(a) classical physics: motion, fluids, heat,
sound, light, electricity and magnetism
 (b) modern physics: relativity, atomic structure,
condensed matter, nuclear physics, elementary
particles and astrophysics
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Why study physics?
(Giambatista et al.)
 Since physics describes matter and its
basic interactions, all natural sciences
are build on a foundation of the laws of
physics.
 In today’s technological world, many
important devices can be understood
correctly with the knowledge of the
underlying physics.
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Light interference produces
shimmering blue color of a
butterfly
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CAT scan
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How a CD is read.
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Fiber optics carry signals
efficiently based on the
principle of total internal
reflection
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Why study physics?
 By studying physics, you acquire skills that are
useful in other disciplines.
 Society’s resources are limited, so it is
important to use them in beneficial ways and
not squander them on scientifically impossible
projects.
 By studying physics, we hope that you develop
a sense of beauty of the fundamental laws
governing the universe.
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The nature of physics
(Cutnell & Johnson)
 The science of physics has developed
out of the efforts of men and women to
explain our physical environment.
 The exciting feature of physics is its
capacity for predicting how nature will
behave in one situation on the basis of
experimental data obtained in another
situation. Such predictions place physics
at the heart of modern technology.
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Length or distances studied
in physics (order of
magnitude)
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Radius of proton or neutron
Atom
Virus
Height of Mount Everest
Earth diameter
Sun diameter
Distance earth to sun
Farthest galaxy visible
10-15 m
10-10 m
10-7 m
104 m
107 m
109 m
1011 m
1026 m
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Some masses (approx.)
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Electron
Proton / neutron
DNA molecule
Mosquito
Person
Ship
Earth
Sun
Galaxy
10-31 kg
10-27 kg
10-17 kg
10-5 kg
102 kg
108 kg
6 x 1024 kg
2 x 1030 kg
1041 kg
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Some time intervals
(approx.)
Lifetime of very unstable sub-atomic
particle
10-23 s
Lifetime of muon
10-6 s
Time between human heartbeats
One year
Human lifespan
Life of earth
Age of universe
100 s (1s)
3 x 107 s
2 x 109 s
1017 s
1018 s
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