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)