introduction physics 100 “physics for poets” stephen l. olsen
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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)