# Document

advertisement ```Chapter 1
Introduction
&copy; 2006, B.J. Lieb
Giancoli, PHYSICS,6/E &copy; 2004. Electronically reproduced
by permission of Pearson Education, Inc., Upper Saddle
River, New Jersey
Ch 1
1
What is Physics ?
•Discipline of Science dealing with the properties of
matter and energy.
•Includes; acoustics, astrophysics, atomic physics,
cryogenics, electromagnetism, elementary particle
physics, fluid dynamics, geophysics, mathematical
physics, mechanics, molecular physics, nuclear physics,
optics, plasma physics, quantum physics, solid state
physics, statistical mechanics, thermodynamics.
Ch 1
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Topics Covered in PHYS 243
• Classical Mechanics
•Fluids
•Vibrations and Waves
•Sound
•Thermodynamics
Ch 1
3
Measurement Uncertainty
In lab you will have to
estimate the uncertainty in
any measurement. The
result might be
X =8.8 cm &plusmn; 0.1cm
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Another way to show
uncertainty is the number
of significant figures – the
number of reliably known
digits, which might be two
in this case.
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Significant Figures
•
0.0034 has two significant figures
•
44.58 has four
•
800 has one (probably) 8.00x102 has three
• the final result of multiplication or division should have only
as many digits as the number with the least number of significant
figures used in the calculation. ( 23.66 x 1.1 = 26 )
• the final result of addition or subtraction is no more accurate
than the least accurate number used.
23.5 + 43.2 + 44 = 111
Ch 1
5
5. Units, Standards and SI System
Length: 1 meter defined as the distance light travels in 1 /
299,792,458 of a second.
Mass: 1 kilogram defined as a standard mass of a certain
cylinder kept near Paris
Unified Atomic Mass: 1 u defined as the 1/12 of the mass of
the 12C atom.
1u = 1.6605 x 10-27 kg
Time: 1 second defined by a cesium clock.
Ch 1
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Metric Prefixes You must know
Ch 1
giga
mega
kilo
G
M
k
109
106
103
centi
milli
micro
nano
c
m

n
10-2
10-3
10-6
10-9
pico
femto
p
f
10-12
10-15
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Math Symbols
x&gt;y
x is greater than y
y&lt;x
y is less than x
y &lt;&lt; x
y is much less than x
yx
y is approximately equal x
yx
y is defined equal to x
x
change in x
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x
i 1
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i
 x1  x2  x3  x4  x5
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Converting Units
•You are strongly urged to use the standard way of doing
units conversion in physics. It reduces errors and is much
easier for the grader to check.
•It is based on the fact that you can multiply any thing by ‘1’
without changing its value.
Example:
1 inch = 2.54 cm Thus
1
2.54 cm
1 in

1 in
2.54 cm
Example: The area of a surface 5.0 in by 3.0 in is
Area  (5.0 in ) ( 3.0 in )
2
 2.54 cm 
2
Area  (5.0 in) (3.0 in) 

97
cm

 1 in 
Ch 1
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Order Of Magnitude Estimate
• It is a good idea to do a rough estimate before doing a
detailed calculation
•When you work a problem, ask yourself if the result
appears reasonable.
Ch 1
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Dimensions and Dimensional Analysis
• In
order to be correct, an answer must have the correct
units.
•Your solution must include units to show how they
work out
•You can often use units to guide you to the answer.
•Useful Rule: We can add or subtract quantities only if
they have the same dimensions.
•Example:
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Each term has units of length.
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