Introduction Physics 100 “Physics for poets” Stephen L. Olsen.
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Transcript of Introduction Physics 100 “Physics for poets” Stephen L. Olsen.
Introduction
Physics 100
“Physics for poets”
Stephen L. Olsen
Class procedures
Put this in your “hotlis
t”
Tentative Schedule
Homework will be graded
About 8 ~ 9 questions per assignment
look on the web page for
hints
What does “Physics” mean?
Greek: φίσίσ
phisis Nature
Chinese: 物理 WU LI
“things” “logic”
“The logic of things”
or “How things work”
What kind of “things”?Ordinary-sized objects::
apples:
footballs:
ukuleles:etc.
Gigantic things
Earth
Sun
galaxies
etc.
Very tiny things
molecules
atoms
cells
quarks
Galileo Galilei
1562 - 1642
One meter of length
1 meter = 40 inches (1.1 yds)
1 centimeter = 1/100 meters (about the radius of a penny)
1 millimeter = 1/1000 meters (about the thickness of a dime)
1 kilometer = 1000 meters (about 5/8th of a mile)
10,000,000m
Coordinate systems
x
z
y
To describe the positionof an object: You needto define a coordinate system (reference frame)& determine 3 coordinates
e.g. x, y & z
Choices of location ofthe coordinate system& directions of the axesare up the observer.
Some distances
• Nose to finger ~1 m• The back of the room ~10 m• Campus Center ~100 m• Varsity theatre ~1000 m• North shore ~50000 m• Center of Earth ~6400000 m• Earth to Moon ~385000000 m• Earth to Sun ~150000000000 m• Next star ~40000000000000000 m
Some small sizes
• radius of a penny ~0.01 m• thickness of a dime ~0.001 m• thickness of a human hair ~0.000075 m• diameter of a red blood cell ~0.00000002 m• size of hydrogen atom ~0.00000000006 m• size of hydrogen nucleus ~0.0000000000000001 m
Exponential logic
Powers of 10
$50000.0 = $5000.00 x 10
Move the decimalpoint 1 place to the
left
multiplyby 10&
$0.01 = $00.1 x 1/10
Move the decimalpoint 1 place to the
right
divide by 10&
Positive powers of 10
150000000000150000000000.15000000000.0 x 1011500000000.00 x 102150000000.000 x 10315000000.0000 x 1041500000.00000 x 105150000.000000 x 10615000.0000000 x 1071500.00000000 x 108150.0000000000 x 10915.0000000000 x 10101.50000000000 x 1011
= 1.5 x 1011
1500000000.00 x 10x10
11 jumps to the left +11 in the exponent
Some distances
• Nose to finger ~1 m• The back of the room ~10 m• Campus Center ~100 m• Varsity theatre ~1000 m• North shore ~50000 m• Center of Earth ~6400000 m• Earth to Moon ~386,000,000 m• Earth to Sun ~150000000000 m• Next star ~40000000000000000 m
~5.0 x 104 m ~6.4 x 106 m ~3.86 x 108 m
~1.5 x 1011 m ~4.0 x 1016 m
Negative powers of 10
0.00000000006 00.0000000006 x 1/10 00.0000000006 x 10 -1000.000000006 x 10 -1x10-1000.000000006 x 10 -20000.00000006 x 10 -300000.0000006 x 10 -4000000.000006 x 10 -50000000.00006 x 10 -600000000.0006 x 10 -7000000000.006 x 10 -80000000000.06 x 10 -900000000000.6 x 10 -10000000000006.x 10 -11
= 6.0 x 10-11
11 jumps to the right -11 in the exponent
Some small sizes
• radius of a penny ~0.01 m• thickness of a dime ~0.001 m• thickness of a human hair ~0.000075 m• diameter of a red blood cell ~0.00000002 m• size of hydrogen atom ~0.00000000006 m• size of hydrogen nucleus ~0.000000000000001 m
~7.5 x 10-5 m ~2.0 x 10-8 m
~6.0 x 10-11 m ~1.0 x 10-15 m
Multiplying large numbersUse the rule:
(A x 10a ) x (B x 10b) = (AxB) x (10ax10b)
Number of people
In the USx Income/person
296,000,000 x $ 40,100
= 2.96x108 x $ 4.01x104
= (2.96 x $4.01) x (108 x 104)
= $11.9 x 108+4 =$11.9 x 1012 = $1.19 x 1013
on8/23/05
10a+b
dividing large numbers
=US national debt# of persons in US
on8/23/05
Ax10a Bx10b
x= = x 10a x 10-b
$7,930,000,000,000296,000,000 persons
$7.93 x 1012
2.96 x 108 persons= =
$7.93 1012
2.96 108 personsx
= $2.68 x 1012- 8 /person
move b upstairs
= $2.68 x 104/person
(= $26,800/person)
AB
AB
10a 10b
& change sign
10a-b
Powers of 10 (film)