Transcript Scaling - MCTCteach

Homework Update
• Complete Homework sections at the end of the
Notes for the first lecture (Tuesday) and
today’s lecture (Thursday) on calendar section
of mctcteach.org/astronomy
– Homework Highlights
• Email me by 11:59pm on January 16, 2015
***Follow Instructions in Notes***
• Complete the first D2L quiz (some questions on test)
• Make 2 flashcards/notecards to bring on Tuesday (write
something on these notecards from the OBJECTIVES
from last lecture or today) – not graded but used for
attendance
•
•
•
•
General Goals
Envision the size of the Earth-Moon
system and the Solar System.
Work with large numbers (scientific
notation).
Work with the metric system.
Design scale models.
Attempts to “comprehend” the
size of the Universe
1. Take virtual trips
2. Use big numbers like 4.2 X 1012
3. Use large units like a light year
4. Use scale models
1. Virtual Trips
•Travel the universe (watched last lecture)
http://micro.magnet.fsu.edu/primer/java/sc
ienceopticsu/powersof10/index.html
http://apod.nasa.gov/apod/ap100120.html
More links in notes
Ranking Exercise
• 1. Complete ranking exercise on your own.
<TWO MINUTES>
• 2. Find two partners. Introduce yourself.
Agree on the rankings. Use the group
sheet this time. Fill it in and hand it in
(PRINT FIRST AND LAST NAMES).
<FIVE MINUTES>
Ranking Exercise
• Rank the following objects from smallest
(1) to largest (5):
4 Solar System
2 Earth
1 Our Moon
5 Milky Way galaxy
3 Average star like our Sun
Ranking Exercise
• Rank the following distances from Earth
(1=closest,…, 6=most distant):
5 Center of Milky Way Galaxy (~27 000 ly)
2 Our Sun
1 Moon
4 Next nearest star (after Sun) (~ 4 ly)
6 Andromeda Galaxy (nearest neighbor
galaxy to ours) (2.5 x 106 ly)
3 Pluto
2. Large (or small) numbers
Brief review of powers of ten:
103 means 10 X 10 X 10 = 1000
Start with 1 and then move the decimal over
3 places to the right.
1
1
1
10  2 

 0.01
10 10 10 100
2
Start with 1 and then move the decimal over
2 places to the left.
Brief review of powers of ten:
108 is 100 000 000
(Use spaces not commas)
10-8 is 0.000 000 01
(Use a 0 in front of the decimal)
Practice problems - handout
http://www.mctcteach.org/astronomy
Review Scientific Notation
6.3 X 102 means
6.3 X 100 which is
630
Scientific notation (handout)
Review Scientific Notation
6.3 X 102
For a short cut, start with 6.3
Then move the
decimal
two places right
Scientific
notation (handout)
giving 630
Review Scientific Notation
2.81 X 104
Start with 2.81
Move the decimal four places right.
28 100
Review Scientific Notation
8.2 X 10-5
Start with 8.2
Move the decimal five places to the left.
0.000 082
Practice problems on handout
(link to file in notes)
3. Units
• Any standard of measurement or exchange
• Ex. In 3 feet, the units are feet
• Ex. In 5.5 s, ?
• Ex. In $6, ?
SI System of Units
• In science, use the SI system
(meter, kilogram, second)
International System of Units (SI Units)
SI Base Unit
Will use in
SI Base Quantity
Astronomy?
Name
Symbol
Yes
Length
meter
m
Yes
Mass
kilogram kg
Yes
Time
second s
Electric current
ampere A
Yes
Temperature
Kelvin
K
Amount of substance mole
mol
Luminous intensity
candela cd
Identify m, cm, mm
• Common Objects
Examples
• Given some lengths, find a common object
that is that size.
– 1 mm
– 1 cm
– 10 cm
– 30 cm
-1m
-2m
-4m
- 10 m
• 1 m ~ 1 giant step, 1 cm ~ thickness of
pencil, 1 mm ~ thickness of paper clip wire
Unit Prefixes
• centi, milli
• nano, micro, milli, centi, kilo, mega, giga
• Handout (link to file in notes)
A List of Metric Prefixes
Memorize for
Astronomy?
No
Yes
Yes
Yes
No
No
Yes
No
Yes
Yes
Yes
Yes
No
Prefix
Symbol
tera
T
giga
G
mega M
kilo
k
hecto h
deca da
no prefix means
deci
d
centi c
milli
m
micro µ
nano n
pico
p
Numerical multiplier
1 000 000 000 000
1 000 000 000
1 000 000
1 000
100
10
1
0.1
0.01
0.001
0.000 001
0.000 000 001
0.000 000 000 001
Power of
Ten
1012 trillion
109 billion
106 million
103
102
101
100
10-1
10-2
10-3
10-6
10-9
10-12
Astronomical Unit
Larger, commonly used unit
Abbreviation – AU
Meaning – Average Earth-Sun distance
(1 AU = 150 000 000 km = 93 000 000 mi)
Ex. How far from Earth to Sun?
Ex. How far from Sun to Pluto?
Ex. How far to edge of our solar system?
Light year
Larger, commonly used unit
Speed of light
= 186 000 mi/s
= 300 000 km/s
= FAST
= 7 ½ times around Earth in one second!!
•**Light-year (symbol ly)
Distance light travels in one year**
1 ly = 1 x 1016m
Example –
Sun to Proxima Centauri ~ 4.2 ly
Light from the Sun takes ~4.2 years to
reach the NEXT nearest star
(~20 000 years by rocket)
http://apod.nasa.gov/apod/ap051204.html
•Light-year (ly)
Andromeda
Galaxy (right)
~ 2.5 Mly
Milky Way
Galaxy diameter
~100 000 ly
(thickness=1000 ly)
•Light-year (ly)
Distant Galaxies
~ 10 billion ly (Bly)
Most distant galaxies
~ 13 Bly
4. Scale Models
• Help picture things so you can think about
them.
• Can be larger or smaller.
• Examples:
1. Architecture: structures, landscapes
2. Toys: Rockets, Dolls
3. Science: Atom, Earth globe
Scale Model of U.S.
• Scale the U.S. to a scale of 1 mm = 10 mi
(equivalently 1 cm = 100 mi and 1 m = 10 000 mi)
• Given data
Twin Cities’ diameter is ~20 mi
Chicago’s diameter is ~50 mi
TC to Chicago is
~600 mi
TC to NYC is
~1000 mi
TC to LA is
~2000 mi
TC to Moon is
~240 000 mi
Scale Model of U.S.
• Question: It is about 1 mi to the downtown
library from here. If you wanted to
represent that distance on your scaled
map, would you use a pencil point dot or
the diameter of a dime to represent that
distance? Explain.
Scale Model of Earth - Moon
• Scale 1 mm = 100 mi (equivalently 1 cm = 1000 mi
and 1 m = 100 000 mi)
• Given data
Earth is 8000 mi in diameter
Moon is 2000 mi in diameter
distance from Earth to Moon is 240 000 mi
What does this look like?
Scale Model of Earth - Moon
• Scale 1 mm = 100 mi (equivalently 1 cm = 1000 mi
and 1 m = 100 000 mi)
• Given data
Earth is 8000 mi in diameter
Moon is 2000 mi in diameter
distance from Earth to Moon is 240 000 mi
Where are these in our model?
International Space Station is 200 mi away
Geosynchronous satellite is 20 000 mi away
Sun is 100 000 000 mi away
Scale Model of Earth – Moon
Using Globe
• Given data
Earth is 30 cm in diameter
Moon is 8 cm in diameter
distance from Earth to Moon is 9 m
What object should we use for the Moon?
How far away should it be from the Earth?
Scale Model of Sun – Earth
• Scale 1 mm = 2000 mi (equivalently 1 cm = 20 000
mi and 1 m = 2 000 000 mi)
• Given data
Sun is 900 000 mi in diameter
Earth is 8000 mi in diameter
Moon is 2000 mi in diameter
distance from Earth to Sun is 100 000 000 mi
distance from Earth to Moon is 240 000 mi
What does this look like?
Homework Update
• Complete Homework sections at the end of the
Notes for the first lecture (Tuesday) and
today’s lecture (Thursday) on calendar section
of mctcteach.org/astronomy
– Homework Highlights
• Email me by 11:59pm on January 16, 2015
***Follow Instructions in Notes***
• Complete the first D2L quiz (some questions on test)
• Make 2 flashcards/notecards to bring on Tuesday (write
something on these notecards from the OBJECTIVES
from last lecture or today) – not graded but used for
attendance