8th Grade Science Final Exam Review

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8th Grade Science Final Exam Review
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1. What are the tests used to identify a
mineral?

• Streak color of a minerals powder.
• Fracture splitting a mineral apart unevenly.
• Cleavage breaks evenly.
• Luster describes how light is reflected from a
  minerals surface.
• Density mass/volume
• Hardness Mohs Scale (Talc 1 Diamond 10)

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2. What is a crystalline structure and how does
it relate to minerals?

• A repeating pattern of a minerals particles.
• All minerals are crystalline.

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3. What are the properties of minerals? Give
two examples of minerals.

• Natural.
• Inorganic no materials were part of living
  things
• Solid
• Crystalline repeating inner structure with the
  same chemical composition throughout.
• Quartz Halite

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4. Describe the three types of rocks, how they
form and an example of each.

• Sedimentary sediments compacted
  together.(Sandstone)
• Metamorphic change due to intense
  heat/pressure(Marble)
• Igneous form from the cooling of magma(Granite)
• Sandstone Marble Granite

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5. Coarse-grained and fine-grained rocks form
differently. Explain the difference.

• Coarse-Grained cools slowly(Granite)
• Fine-Grained cools quickly(Basalt)
• Basalt Granite

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6. Draw the rock cycle. Why do there need to be
multiple sets of arrows?

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7. What is the difference between an earthquake
and an aftershock?

• Earthquake the main earthquake that happens
  first
• Aftershock smaller earthquakes that occur in
  the same focus days to years after the main
  event.

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8. What is the difference between the epicenter
and focus of an earthquake?

• The earthquakes focus is the point within the
  earth where the earthquake originates.
• The epicenter of an earthquake is the point on
  the surface of the earth directly above the
  focus.

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9. Describe the Richter Scale in terms of values
and how its measured.

• Measures the amount of energy released by an
  earthquake.
• Measured using distance from the epicenter and
  wave amplitude.

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10. What are the three types of plate boundaries?
How do they interact?

• Divergent plates separate
• Transform plates slide past one another
• Convergent plates collide together
• Continental-Continental push up and form
  mountains
• Continental-Oceanic collide and form volcanic
  mountains
• Oceanic-Oceanic collide and forms volcanic
  islands

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11. What geological features are found where the
following types of crust collide ?

• Continental-Continental mountains
• Continental-Oceanic Volcanic Mountains
• Oceanic-Oceanic Volcanic Islands, Ocean
  Trenches

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12. What is the difference between P and S waves
and Surface waves?

• P-Waves arrive at the surface first, move by
  compressing and expanding the ground like a
  slinky
• S-Waves arrive at the surface second, move side
  to side, slower than P-Waves
• Surface Waves these waves move slower than
  P-Waves and S-Waves.

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13. List some ways that mountains can form?

• Convergent continental plates form mountains.
• Convergent continental and oceanic plates form
  volcanic mountains.
• Hot spots form volcanic island mountains

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14. What type of rock makes up most of the ocean
floor?

• Basalt which is a fine-grained rock.
• Basalt

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15. How is volcanic ash formed?

• Volcanic ash is formed from exploding pumice.

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16. Why do volcanoes form where plates collide?

• Magma forms from the oceanic crust melting
  through the process of subduction. The magma
  rises because it is less dense than the
  surrounding rock and its lava forms a volcano
  when it reaches the surface.

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17. Name the three types of volcanoes and how
each forms.

• Shield very runny lava, shortest but widest
• Composite tall and pointy, very viscous lava,
  alternating eruptions of cinder or ash and lava
• Cinder Cone consist primarily of loose cinder
  around a single vent

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18. How does a caldera form?

• An explosive eruption that causes a collapse of
  surface rock into an empty magma chamber

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19. How will the viscosity of lava affect the
shape of the active volcano ?

• Thick lava tall pointed volcanoes
• Thin lava wide, short volcanoes

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20. What evidence do we have to suggest that the
continents were once connected ? What is the
name of the theory that states that the plates
are in constant movement?

• Strings of mountains and fossils across
  continents that are no longer connected.
• The continents fit together like pieces to a
  puzzle.
• Plate tectonics is the theory that stated that
  all of the plates are in constant motion
• Pangea is the name of the supercontinent that
  existed million of years ago.

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21. Describe how you determine whether an object
is in motion or not.

• If the object changes position relative to a
  reference point.
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22. Explain why reference points that are
stationary are usually chosen to determine
whether an object is in motion.

• If the reference point is moving its hard to
  tell if the object is in motion.
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  airspace/doppler/en/doppler_exp.htm?width750heig
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23. How do you calculate an objects speed?

• Total Distance/Total Time

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24. Describe what velocity is.

• Speed in a given direction.

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25. Demonstrate how to graph motion. Write a
basic problem, solve the problem and then graph
it.

• Use a line graph in which you plot time versus
  distance, the steepness of a line on a graph is
  called its slope. Sloperise/run

Distance
Time
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26. Describe the motion of an object as it
accelerates.

• A change in the speed or direction of an object

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27. Demonstrate how to graph acceleration.
Write a problem, then solve and then graph it.

• Acceleration Final Speed-Initial Speed/Time
• To graph you can use both a speed-versus-time-grap
  h and a distance-versus-time graph

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28. Describe what a force is.

• A push or a pull on an object.

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29. Describe how balanced and unbalanced forces
are related to an objects motion.

• Balanced forces will not cause a change in motion
  of a moving object.
• Unbalanced forces cause an object to move in the
  direction the larger force is moving.

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30. Describe friction and identify factors that
determine the friction between two objects.

• A force that opposes motion through two surfaces
  that are in contact
• The force pushing the surfaces together and the
  roughness of the surface

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31. Identify the factors that affect the
gravitational force between two objects.

• The two factors are mass and distance
• The more mass more force between it
• Gravitational force depends on the distance
  between the objects centers
• As the distance increases, the gravitational
  force decreases.

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32. State Newtons Three Laws of Motion and
give an example of each

• 1st law An object at rest will remain at rest
  unless acted upon by a nonzero force. An object
  moving at a constant velocity will continue to
  move at a constant velocity unless acted upon by
  a nonzero net force.
• Ex. A ball will not move unless a force is put
  upon it.

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32. State Newtons Three Laws of Motion and give
an example of each.

• 2nd law An objects acceleration depends on its
  mass and the net force acting on it.
• Acceleration net force/mass
• Ex a cart goes faster when something falls out

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32. State Newtons Three Laws of Motion and give
an example of each.

• 3rd law If one objects exerts force on another
  object, then the second object exerts a force of
  equal strength in the opposite direction of the
  first object. For every action there is an equal
  but opposite reaction
• Ex. A swimmer moves because the water pushes her
  forward when she pushes back on it

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33. Explain how momentum is determined and
conserved.

• Momentum Mass x Velocity
• Law of conservation of momentum states the in the
  absence of outside forces like friction, the
  total momentum of objects that interact does not
  change
• Ex. The amount of momentum two cars have is the
  same before and after they interact

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34. Describe the motion of an object during free
fall.

• Free fall is the constantly accelerating motion
  that occurs when the only force acting on an
  object is gravity.

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35. What factors keep objects in orbit around
the Earth?

• Objects stay in orbit because gravity supplies
  centripetal force.

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36. What is work and how can it be determined?

• Work is done on an object when the object moves
  in the same direction in which the force is
  exerted.
• Work Force x Distance

WORK
NOT WORK
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37. Define power

• Power equals the amount of work done on an object
  in a unit of time
• Power Force x Distance/Time

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38. How do machines make work easier?

• A machine makes work easier by changing at least
  one of three factors
• 1. The amount of force you exert
• 2. The distance over which you exert your force
• 3. The direction in which you exert your force

Changing Distance
Changing Direction
Changing Force
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39. How can we calculate the mechanical
advantage and efficiency of a machine?

• Mechanical advantage is the number of times a
  machine increases a force exerted on it.
• Mechanical advantage Output force/input force
• Efficiency of a machine compares output work to
  input work
• Efficiency Output work/Input work x 100

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40. Describe how we can calculate the mechanical
advantages of inclined planes, wedges and
screws. List the formula used to calculate each.

• Inclined Plane length of the incline/height
• The ramp with the smallest mechanical advantage
  is the steepest
• Wedges length of the wedge/width of the wedge
• The longer and thinner a wedge is, the greater
  the mechanical advantage
• Screws length around threads/length of screw
• The closer together the threads of a screw are,
• the greater the mechanical advantage

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41. Classify and describe the mechanical
advantage of each class of lever. List the
formula used to calculate each.

• First Class mechanical advantage can be less or
  greater than 1 depending on the fulcrum
• Second Class mechanical advantage is always
  greater than 1
• Third Class mechanical advantage is always less
  than 1  
• Formula distance from fulcrum to input
  force/distance from fulcrum to output force

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42. Describe the mechanical advantages of
pulleys and wheel and axles. What formula would
you use to calculate each?

• Pulleys
• Fixed Pulley changers the direction of force but
  not the amount applied (MA 1)
• Moveable Pulley changes the direction of the
  force
• (MA 2) 
• Block and Tackle pulley system made up of fixed
  and movable pulleys (MA 3)
• MA the number of pulleys

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42. Describe the mechanical advantages of
pulleys and wheel and axles. What formula would
you use to calculate each?

• Wheel and Axle
• The greater the ratio of the wheel radius to the
  axle radius, the greater the advantage
• Formula Radius of wheel/Radius of axle

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43. Describe the mechanical advantages of
compound machines and how do we calculate the
advantage for them?

• The mechanical advantage of each simple machine
  is not affected by the other machines, but their
  mechanical advantages combine to produce the
  mechanical advantage of the whole machine
• Formula multiply the mechanical advantages of
  the simple machines that make up the compound
  machine

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44. Explain how energy, work, and power are
related. Use a Venn diagram.

•    

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45. Name and describe the two basic types of
energy.

• Kinetic Energy the energy that an object has
  due to its motion
• Potential Energy the energy an object has
  because of its position or shape

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46. What are the six forms of energy? Give an
example of each.

• Mechanical energy ex. Falling basketball and
  moving car
• Nuclear energy ex.nuclear power plant
• Thermal energy ex. A heated pot of water at 75
  degrees has more thermal energy than the same
  water at 30 degrees
• Electrical energy ex. lightning
• Electromagnetic energy ex. microwaves and x-rays
• Chemical energy ex. bonds are broken in your
  cells release energy for your body to use

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47. What does the law of conservation of energy
state?

• When one form of energy is transformed to
  another, no energy is lost in the process.
  Energy cannot be created or destroyed.

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48. Explain how static electricity builds up and
transfers.

• Static electricity is an imbalance between
  negative and positive charges in objects. Static
  electricity transfers when the rubbing of certain
  materials against one another can transfer
  negative charges, or electrons.
• Static discharge is the loss of static
  electricity as electric charges transfer from one
  object to another.

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49. What are the differences between from
conductors and insulators? List two of each.

• Conductors allow electrons to flow easily
• example most metals
• Insulators do not allow electrons to flow easily
• ex. air and wool and rubber

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50. Using a diagram, describe the basic features
of an electric series and parallel circuit.
Wire
Wire
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51. What causes charges to move through a
circuit?

• Voltage or difference in electric potential
  energy

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52. Explain Ohms Law. What is the formula to
calculate resistance?

• Ohms Law describes how voltage, current, and
  resistance are related.
• Voltage Resistance x Current
• The unit is Ohms O

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53. How do you calculate electric power and
energy use?

• Power (Watts) Voltage (V) x Current (A)
• Current (A) Power (Watts) /Voltage (V)
• Energy (kWh) Power (kW) x Time (hours)

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54. Identify each property of a magnet.

• magnets attract iron and materials that contain
  iron, nickel and cobalt.
• magnets attract opposite poles and repel the same
  poles of other magnets
• magnets, when freely swinging, one end always
  points north

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55. Explain how magnetic poles interact.

• Each magnet has two ends, each called a magnetic
  pole. Magnetic poles that are unlike attract
  each other, and magnetic poles that are alike
  repel each other.

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56. What is a magnetic field?

• The area of magnetic force around a magnet. The
  magnetic field lines spread out from one pole,
  curve around the magnet, and return to the other
  pole.

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57. Describe the characteristics of solenoids
and electromagnets

• Solenoids a coil of wire with a current, the two
  ends act like the poles of a magnet
• Electromagnets are solenoids with a
  ferromagnetic core, the overall magnetic field of
  an electromagnet is much stronger than that of a
  solenoid. Turning the current off and on turns
  the electromagnet off and on.

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Solenoid
Electromagnet
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58. Explain how mechanical energy can be
converted to electrical energy in a generator.

• A generator uses motion in a magnetic field to
  produce current. The slip rings turn with the
  armature and transfers current to the brushes.
  The crank rotates the armature. The motion of the
  armature in the magnetic field induces a current
  and when the brushes are connected to a circuit,
  the generator can be used as an energy source.

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59. Explain the difference between an
alternating and direct current.

• Alternating Current a constantly reversing
  current
• Ex. Electricity through a wall outlet
• Direct Current a current with charges that flow
  in one direction
• Ex. Battery

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60. Explain how the Doppler Effect relates to
pitch.

• The change in sound waves changes the frequency
  and is heard as a change in pitch.
• Sound waves in front of a moving object are
  shortened and have a higher frequency and higher
  pitch
• Sound waves trailing behind a moving object are
  lengthened have a lower frequency and lower
  pitch.

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61. What property of sound waves affects the
pitch of a sound? What property of sound waves
affects the loudness of a sound?

• Loudness determined by amplitude of a wave
• High amplitude loud Low amplitude high
•  Frequency determines pitch
• High frequency high pitch Low frequency low
  pitch

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62. Describe how sound intensity changes with
the distance. Give an example.

• Intensity decreases as the distance increases
• Ex. Standing behind a fire trucks siren
• Intensity increases as the distance decreases
• Ex. Standing in front of a fire trucks siren

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63. How is music different from noise?

• Music is a set of notes that combine in patterns
  that are pleasing. The vibrating chords set air
  particles into vibration.
• Noise is unwanted sound. Some examples are a
  running engine, operating a machine, and loud
  tools.

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64. List and describe two different ways that
animals and people use sound waves.

• Animals (bats and dolphins) use echolocation to
  navigate and find food, bats use ultrasound which
  are sound waves with frequencies above the human
  range of hearing.
• People use sonar and ultrasound imaging to
  observe things they cannot see directly. People
  use sonar to detect and locate objects under
  water, depth of water and to map the ocean floor
  and sonograms.

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65. List and describe two ways in which a
surface can reflect light.

• regular reflection (aka specular reflection)
  parallel rays of light hit a smooth surface, the
  image is a copy of the object formed by
  reflection or refracted rays of light
• diffuse reflection parallel rays of light hit
  an uneven surface, an unclear image is seen, most
  objects reflect light diffusely.

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66. What is the difference between primary and
secondary colors of light?

• Primary are three colors that combine to make any
  other color (red,green,blue)
• Secondary is when the three primary colors of
  light are combined in equal amounts.

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67. Compare plane, concave and convex mirrors in
terms of the type of surface they have and the
type of image that they produce.

• Plane mirror has a flat surface, the image is
  upright and the same size as the object.
• Concave mirror has a surface curved inward, it
  produces a real or virtual image, depends on the
  distance.
• Convex has a surface that curves outward, it
  always produces a virtual image that is smaller
  than the object.

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Convex mirror
Plane mirror
Concave mirror
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68. Explain how refraction of light occurs.
Give an example of refraction.

• When light rays enter a medium at an angle, the
  change in speed causes the rays to bend. Ex. A
  rainbow

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69. Use the terms retina, rods, cones and optic
nerve to explain how an image is formed and
interpreted by the human eye.

• Light enters through lens and a real image is
  projected onto retina
• Retina layer of cells that line the inside of
  the eyeball
• Rods cells in the retina that respond to small
  amounts of light
• Optic Nerve carries signals from the eyes to the
  brain

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70. When comparing your body to a simple
machine, most of the bodies bones and muscles
work to act together as what type of machine?

• Levers