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EARTH SCIENCE REGENTS REVIEW
TOPIC 1: OBSERVATION AND MEASUREMENT OF THE ENVIRONMENT
* Observations involve using the senses to gather information -- all the senses, not just sight
* Our senses are limited (ex/ we can only see so far) so observations can be improved by extending the senses through the use of instruments (telescopes, meter sticks, etc.)
* Inferences are conclusions or predictions based on observations (they may or may not be accurate)
EX/ observations about a mineral: 3 planes of cleavage, clear, tastes salty
inference: the mineral is halite
* Classification is the grouping of things according to similar properties, or, organizing things to make studying them easier [by classifying things based on good observations, we make valid inferences]
UNITS OF MEASUREMENT
* mass: the amount of matter in an object, measured in grams
* weight: a measurement of the amount of gravity pulling on an object -- it depends on the object’s distance from the Earth’s center [mass doesn’t change as you leave the Earth, but weight does (“weightlessness”)] For objects located at or near the Earth’s surface, mass is measured by weighing the object
DETERMINING ERROR IN MEASUREMENT
* percent error / percent deviation {formula in Reference Tables}
Write out the formula! Then plug in numbers! Most often, people forget to multiply by 100......
If you write out the formula and then plug in numbers, you won’t miss any of the steps!
EX/ The actual mass is 100 grams and the measured mass is 95 grams. (remember, the word “difference”
means “subtract” the numbers!) Difference between actual / accepted and the measured values is 5
grams; divide 5 grams by the actual/accepted value of 100 grams and you get .05. Now, multiply this
by 100 and you get 5% error
DENSITY
* Density = mass per unit of volume (or mass ÷ volume) {formula in RT} (mass is in grams, volume is in cm3, cc, or ml)
* When the density is given and you have to determine either mass or volume, use the density formula, put Density over 1.0 and plug in given values, then cross multiply. On a multiple choice question, use trial and error: ex/ if density and mass are given in the problem and you have to find the volume, plug in each volume choice given and the mass into the density formula and see which one comes up with the value for density that they gave you. ALWAYS DOUBLE CHECK!!!!!!!!
* Remember, the density of a substance doesn’t change if it is cut up smaller or more of it is added!
EX/ If something has a mass of 100 g and a volume of 50 ml, the density is 2 g/ml.
If it is cut in half, mass = 50 g, and volume = 25 ml, the density is still 2 g/ml
If it is doubled in size, mass = 200 g, and volume = 100 g, the density is still 2 g/ml
* Density only changes if the temperature or pressure changes
* Temperature: if you increase the temperature, molecules move around more, taking up more space/volume -- so the density decreases (ex/ smoke rises, a hot air balloon)
* Pressure: if you increase pressure, you compact the same amount of matter into smaller space/volume -- so the density increases (ex/ basketball vs. bowling ball) This rule applies mostly to gases (because molecules are more free to move) and less to liquids and solids.
* Most materials are most dense in the solid phase (molecules are packed closer together)
* Water is the exception -- most dense as a liquid at 4oC {on RT}
* Energy exchange occurs along an interface: where materials with different properties meet (ex/ wind & waves)
* Dynamic equilibrium: a state or condition of balance (look for key words: “same,” “equal,” or “balance”)
[the Earth as a whole is in a state of dynamic equilibrium, but it is altered by human activities]
* Relationships: plug in numbers on the graph, make X’s, connect X’s with a line
• direct relationship: both things increase together or decrease together
• inverse relationship: one thing increases while the other decreases
• constant / no relationship: one thing stays the same as the other thing changes
TOPIC 2: MEASURING THE EARTH
* The Earth’s true shape is an oblate spheroid (“squashed sphere”) -- bulging at the equator and flat at the poles
[you weigh less at the equator because you are farthest from the center of the Earth]
* The bulging, however, is so small that it can barely be noticed -- therefore, the best model for the shape of the Earth would be something that is perfectly round and smooth -- like a billiard ball or ping pong ball
* Evidence for the Earth’s shape comes from:
• The altitude of Polaris -- if the Earth were flat, the altitude of Polaris would always = 90o
• Gravity measurements -- gravity is slightly less at the equator, slightly more at the poles
• Lunar eclipses -- the curved shape of Earth is seen as a shadow on the moon
• Ships disappear over the horizon from the bottom up
* The best evidence for the true shape of the Earth is actual photographs of the Earth from space
EARTH’S ZONES
* Atmosphere: layer of gases surrounding the Earth (divided into several layers, on RT)
* Hydrosphere: layer of liquid water surrounding the Earth (think “hydroelectric power”, “dehydration”)
* Lithosphere: layer of solid rock surrounding the Earth
LATITUDE AND LONGITUDE
* Latitude lines go across (think “lat / flat” or “lat / ladder”) and measure locations north or south of equator
[also called parallels, because all latitude lines are parallel to each other]
* Longitude lines go up and down (all lines are long) and measure locations east or west of prime meridian [also called meridians] [prime meridian goes through Greenwich, England]
* Equator = 0o latitude ; Prime Meridian = 0o longitude; International Date Line = 180o longitude
* Remember when determining the directions of north, south, east and west: east and west spell “WE”
* Time is determined by longitude (think of the longitude lines that make up time zones for TV programs) Since the Earth rotates 360o (one circle) in 24 hours, 360 ¸ 24 = 15o per hour -- so for every 15 degrees of longitude, time changes one hour -- ahead on the clock if the location is east, behind on the clock if the location is west (think of California on the west coast being behind us on the clock)
* If the time is known in Greenwich and the time is known where you are, you can determine longitude
EX/ It is 3 p.m. in Greenwich and 7 p.m. where you are. The difference in time is 4 hours. For every hour,
there is 15o of longitude. 15 x 4 = 60. Since you are ahead on the clock, you are east of Greenwich, so
you are at 60o East longitude.
EX/ It is 7 a.m. in Greenwich and you are at 45o West longitude. 45 ¸ 15 = 3, so your time is 3 hours
different from the time in Greenwich. You are west, therefore you are behind on the clock, so it is 4 a.m.
where you are.
* Latitude is measured by the altitude of Polaris in the Northern Hemisphere (Polaris is the North Star and can’t be seen in the Southern Hemisphere) Your latitude is equal to the altitude of Polaris!!!!!!
EX/ Where you are, Polaris is found at an angle of 38 degrees above the horizon -- you’re at 38o N lat.
[on the equator, altitude of Polaris = 0o; at the North Pole, altitude of Polaris = 90o]
FIELDS
* Isoline: a line connecting points of equal value -- they never cross!
* Gradient is shown by the closeness of isolines -- lines close together = steep gradient {formula on RT}
* Contour interval: the difference in elevation between adjacent contour lines
* To determine which way a stream is flowing on a contour map:
1. streams always flow downhill -- look for higher elevations for the source of stream, flowing toward lower
elevations
2. contour lines always point (bend) upstream
* Remember: when measuring the distance between two points, always use a scrap piece of paper and make several measurements along straight portions of the route, turning the paper as you go.
TOPIC 3: EARTH IN THE UNIVERSE
* The Earth is a planet which revolves around the Sun. The Moon is a satellite that revolves around the Earth. The Sun is a star. The nine planets {RT} and their moons, as well as the asteroids between the planets, revolving around our Sun make up the Solar System.
* Our Solar System is one of billions within our galaxy, The Milky Way. The Milky Way is one of billions of galaxies in the universe.
* The Big Bang Theory is the most widely accepted theory for the creation of the universe. It basically states that all matter and energy started out concentrated in a small area and, after a gigantic explosion, matter begin to organize into subatomic particles and atoms. This is believed to have occurred approximately 15 billion years ago. Evidence for the Big Bang includes the fact that galaxies are moving away from us and each other.
* The Doppler Effect is the shifting of wavelengths (colored lines) in a spectrum due to an object moving toward or away from the observer.
If the object is moving toward the observer, the electromagnetic waves are bunched together resulting in a blue shift.
If the object is moving away from the observer, the electromagnetic waves are spread out resulting in a
red shift.
* The Milky Way galaxy is about 100,000 light years across and has a spiral shape. We are located towards the end of a spiral arm.
* A light year is the distance light travels in one year (9.5 trillion kilometers)
* The Sun is an average star (part of the Main Sequence) and is about half-way through its life cycle. It gets its energy from nuclear fusion reactions in which hydrogen nuclei combine to form helium nuclei, giving off tremendous amounts of energy
* Luminosity refers to a star’s brightness, compared to the Sun, if it were the same distance as the Sun. Generally, hotter stars have a color toward the blue end of the spectrum and a greater luminosity {RT}
* Stars are formed in gas and dust clouds (nebulae) and go through stages, depending mostly on their mass. They start out as a main sequence star, then explode into either a red giant or a supergiant, depending on the mass. A red giant may then collapse into a white dwarf and then a black dwarf (dead star). A supergiant could explode into a supernova and become either a neutron star or a black hole.
* The Solar System is about 4.5 billion years old. Individual planetary characteristics are in the Reference Tables.
* A geocentric model of the solar system has the Earth at the center, with planets, moon, and sun revolving around it in circular orbits (this was the first model of the solar system)
* A heliocentric model of the solar system has the Sun at the center, with planets moving around it, and the moon moving around the Earth, all in circular orbits, and the stars stay in one place
* The heliocentric model was improved by Kepler’s elliptical orbits, which explained why heavenly objects appear to change in size.....because our distance from them changes (objects that are closer appear to be bigger)
KEPLER’S LAWS
* The eccentricity of an ellipse (elliptical orbit) can be determined by dividing the distance between foci by the length of the major (longest) axis of the ellipse {formula on RT}. It is always a value between zero and 1.0. Use the centimeter ruler on the cover of the RT.
[eccentricity is how “flat” a circle is, therefore, if the eccentricity value is close to zero, it’s close to a perfect circle; if the value is close to 1.0, it is very “flat” or “eccentric”]
* The Earth’s orbit is a slightly eccentric ellipse
* If the Earth’s orbit was a perfect circle, it would always travel at the same speed around the Sun. Because it is elliptical, sometimes the Earth is closer to the Sun (January) so it travels faster and the Sun appears larger. When it is farther from the Sun (June) it travels slower and the Sun appears smaller.
* The larger the radius of a planet’s orbit, the longer its period of revolution [also stated: the farther a planet is from the Sun, the longer it takes to get around it]
* Gravitational force between two objects depends on the masses of the objects and the distance between them. {formula on RT} Since distance is squared in the formula, distance has more effect on gravitational force than mass. Mass and force have a direct relationship: as mass increases, force of attraction between the objects increases. Distance and force have an inverse relationship: as distance between objects increases, force between them decreases.
* When a planet is closest to the Sun, its speed is greater, force of attraction is greater, kinetic energy is greater
TOPIC 4: THE EARTH MODEL -- EARTH MOTIONS
* The apparent daily motions of the stars, moon, sun, and planets are due to the Earth’s rotation -- so everything moves generally from east to west at approximately 15o per hour (the speed the Earth rotates)
* Rotation: spinning on an axis
* Revolution: orbiting around an object
[if you get confused, look up the Solar System Data Table in the Reference Tables -- when you see that the Earth’s period of rotation is 24 hours, you will realize that a “day” is caused by spinning; when you see that the Earth’s period of revolution is 365 days, you will realize that a “year” is caused by orbiting the Sun]
PHASES OF THE MOON
* Remember to put yourself on the diagram of the Earth and it may be necessary to turn your paper around
* The Earth, Sun, and Moon are rarely on the same plane -- even though once each month the Moon is between the Earth and Sun, which would produce a solar eclipse, they are not usually at the same level -- the Moon may be much higher than the Earth and therefore not in the path of the Sun’s rays