Review for Exam 1

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Review for Exam 1

• 2950
• Dr Bryce

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What to expect

• 25 multiple choice questions
• 4 possible responses
• Minimum 20 minutes
• Maximum 50 minutes (depending on how promptly we
  start)
• Exam conditions from the moment the papers are
  distributed.

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What to bring

• Sharp number 2 pencils
• Eraser
• Calculator
• University ID card
• All are vital

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What not to bring

• Heavy bulky bags/jackets (leave at back of class)
• Food/Drink for disturbance/spillage reasons
• Cell phones
• Baseball caps/hats must be removed
• No headphones/earpieces

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Results

• Correct answers will be posted on the course
  website within a few hours
• Scores will be posted on ICON within a few days
• You can take exam papers with you, so you may
  want to discretely mark your answers

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How to succeed

• Read questions carefully and thoroughly
• Bubble in answers carefully
• Erase wrong answers completely
• Fill in name and ID information carefully

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Seating

• Prompt seating of all students is essential in
  allowing full 50 minutes of exam time
• Sit as close to the front/centre as possible
• Leave room for late comers at aisle seats

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Study tips

• Try the online quizzes at www.mhhe.com/fix
• Try to replicate exam conditions so that you can
  concentrate in the exam
• Talk with your classmates, ask them questions,
  put things into your own words
• Visit the astronomy tutorial sessions to work
  through troubling issues, ie phases of the Moon,
  Newtons laws
• Try to condense your notes what are the
  important points

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Basic observations

• Scientific Theory
• The celestial sphere
• Stars rise and set (or are circumpolar)
• What we see depends on the time of year and our
  latitude
• Tilt of the Earths axis causes the seasons
• Phases of the Moon, eclipses
• Retrograde motion

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The History of Astronomy

• Motivation for interest, Calendars, predicting
  eclipses, cycles of Moon and Planets
• Ancient Greek model, perfect circles, geocentric
• The Copernican revolution
• Keplers laws of motion
• Galileos observations

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Physical Laws

• Vocab for describing motion
• Mass versus weight
• Newtons three laws
• Conservation
• Energy
• Temperature
• Universal law of Gravitation

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Equations and Numbers

• You dont need to know exact numbers, ie the
  value of the Gravitational constant but it is
  good idea to have a grasp of scale, ie the
  Gravitational constant is a very small number
• Equations Newtons laws of motion and
  gravitation, Keplers third law

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Scientific Theory

• Scientific theories are designed to be tested
• A theory that cannot be tested (even at a point
  in the future) is poorly thought out.
• Accepted theories have been subjected to many
  tests and we sometimes use the word law, eg Law
  of Gravitation.
• A theory can only be proved wrong, not right.
• Theories explain real life!
• Not to be confused with belief or faith.

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Kelvin temperature scale

• Absolute zero is 0 Kelvin
• Absolute zero is the point at which atoms would
  have zero kinetic energy
• Only positive temperatures using Kelvins

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The horizon system

• The zenith is the point directly above your head
• Altitude is the angular distance above the
  horizon, the zenith is at an altitude of 90o, the
  horizon is 0o (latitude)
• Azimuth is the angular distance measured east
  from north, north is 0o, east 90o, south is 180o,
  west is 270o (longitude)

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More Celestial Sphere definitions

• The Celestial equator is the projection of the
  Earths equator
• The North Celestial pole is the projection of the
  Earths North Pole
• Polaris, the pole star lies very close the the
  North Celestial pole

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The Motion of the Sun

• Throughout the year the Sun appears to move
  relative to the background stars
• The constellations through which the Sun passes
  have well know names the Zodiac
• The Sun moves at a rate of about 1 degree a day

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The Suns path

• The Suns path across the Celestial Sphere is
  called the Ecliptic
• Tilted in relation to the Celestial Equator
• This means that the Suns declination changes
  throughout the year
• NOTE the vernal equinox

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Dates to remember

• Sept 22, Autumnal Equinox, Sun will rise in the
  East and set in the West, the day and night will
  be of equal length.
• Dec 21, Winter Solstice, Sun rises in SE sets in
  SW, least amount of day
• March 21, Vernal Equinox
• June 21, Summer Solstice, Sun rises in NE, sets
  in NW, longest day

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Phases of the Moon 29.5-day cycle
new crescent first quarter gibbous full gibbous la
st quarter crescent

• waxing
• Moon visible in afternoon/evening.
• Gets fuller and rises later each day.

• waning
• Moon visible in late night/morning.
• Gets less and sets later each day.

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So we dont get eclipses every month
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Westwards motion?

• We see the Sun, Moon and the Superior Planets
  moving Eastwards relative to the Stars
• But occassionally we see Westwards motion

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Modern Science and the Greeks

• Greeks were the first people known to make
  models of nature.
• They tried to explain patterns in nature without
  resorting to myth or the supernatural.

Greek geocentric model (c. 400 B.C.)
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Pythagoras model of the Solar System

• Based on perfect circles and perfect spheres
• The Earth is a sphere, an idea that was commonly
  accepted at the time
• The Earth, Sun and Moon are all constantly in
  motion

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Ptolemy explained retrograde motion using
epicycles
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Copernicus (1473-1543)

• Proposed Sun centre-ed Heliocentric Solar System
  model in 1543
• Planets still moved on perfect circles
• No contemporary observations could differentiate
  between the Geo and Helio centric models

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Parallax
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Keplers First Law The orbit of each planet
around the Sun is an ellipse with the Sun at one
focus.
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Keplers Second Law As a planet moves around its
orbit, it sweeps out equal areas in equal times.

• means that a planet travels faster when it is
  nearer to the Sun and slower when it is
  farther from the Sun.

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Keplers Third Law

• More distant planets orbit the Sun at slower
  average speeds, obeying the relationship
• p2 a3
• p orbital period in years
• a avg. distance from Sun in AU

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Galileo Galilei (1564-1642)
Galileo overcame major objections to Copernican
view. Three key objections rooted in Aristotelian
view were

• Earth could not be moving because objects in air
  would be left behind.
• Non-circular orbits are not perfect as heavens
  should be.
• If Earth were really orbiting Sun,wed detect
  stellar parallax.

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Motion?

• Speed the rate at which an object moves, units
  are meters per second or ms-1 or m/s
• Velocity speed and direction
• Acceleration the change in velocity, units are
  meters per second per second or ms-2 or m/s2
• In our day to day life we will often speak of
  miles per hour or the numbers of seconds it takes
  a car to go from 0 to 60 (again mph)
• 1 meter per second is about 2.2 mph

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Acceleration

• We tend to think of acceleration as objects
  increasing in speed
• In fact acceleration occurs whenever there is a
  change in speed positive or negative
• AND when there is a change in direction

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Newtons first law of motion

• An object moves at constant velocity, unless a
  net force acts to change its speed or direction.

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Newtons second law of motion

• Force mass acceleration

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Newtons third law of motion

• For every action there is an equal and opposite
  reaction

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Types of Energy

• Kinetic
• Radiative
• Stored or potential
• Energy can change types, but it cannot be created
  or destroyed.

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Atomic Terminology

• Atomic Number number of protons in nucleus
• Atomic Mass Number number of protons neutrons

• Molecules consist of two or more atoms (H2O,
  CO2)