1. 8 th Grade Science Final Exam Review

2. 1. What are the tests used to identify a mineral? Streak – color of a mineral’s powder. Fracture – splitting a mineral apart unevenly. Cleavage – breaks evenly. Luster – describes how light is reflected from a mineral’s surface. Density – mass/volume Hardness – Moh’s Scale (Talc = 1: Diamond = 10)

3. 2. What is a crystalline structure and how does it relate to minerals? A repeating pattern of a mineral’s particles. All minerals are crystalline.

4. 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. QuartzHalite

5. 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) SandstoneMarbleGranite

6. 5. Coarse-grained and fine-grained rocks form differently. Explain the difference. Coarse-Grained = cools slowly(Granite) Fine-Grained = cools quickly(Basalt) BasaltGranite

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

8. 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.

9. 8. What is the difference between the epicenter and focus of an earthquake? The earthquake’s 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.

10. 9. Describe the Richter Scale in terms of values and how it’s measured. Measures the amount of energy released by an earthquake. Measured using distance from the epicenter and wave amplitude.

11. 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

12. 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

13. 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.

14. 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

15. 14. What type of rock makes up most of the ocean floor? Basalt which is a fine-grained rock. Basalt

16. 15. How is volcanic ash formed? Volcanic ash is formed from exploding pumice.

17. 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.

18. 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

19. 18. How does a caldera form? An explosive eruption that causes a collapse of surface rock into an empty magma chamber

20. 19. How will the viscosity of lava affect the shape of the active volcano ? Thick lava = tall pointed volcanoes Thin lava = wide, short volcanoes

21. 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.

22. 21. Describe how you determine whether an object is in motion or not. If the object changes position relative to a reference point. http://www.planetseed.com/files/flash/science/lab/airspace /doppler/en/doppler_exp.htm?width=750&height=460&pop up=true

23. 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 it’s hard to tell if the object is in motion. http://www.planetseed.com/files/flash/science/lab/airspace /doppler/en/doppler_exp.htm?width=750&height=460&pop up=true

24. 23. How do you calculate an object’s speed? Total Distance/Total Time

25. 24. Describe what velocity is. Speed in a given direction.

26. 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. Slope=rise/run Time Distance

27. 26. Describe the motion of an object as it accelerates. A change in the speed or direction of an object

28. 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-graph and a distance-versus-time graph

29. 28. Describe what a force is. A push or a pull on an object.

30. 29. Describe how balanced and unbalanced forces are related to an object’s 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.

31. 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

32. 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 object’s centers As the distance increases, the gravitational force decreases.

33. 32. State Newton’s Three Laws of Motion and give an example of each 1 st 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.

34. 32. State Newton’s Three Laws of Motion and give an example of each. 2 nd 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

35. 32. State Newton’s Three Laws of Motion and give an example of each. 3 rd 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

36. 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

37. 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.

38. 35. What factors keep objects in orbit around the Earth? Objects stay in orbit because gravity supplies centripetal force.

39. 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 NOT WORK WORK

40. 37. Define power Power equals the amount of work done on an object in a unit of time Power = Force x Distance/Time

41. 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 Force Changing Distance Changing Direction

42. 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%

43. 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

44. 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

45. 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

46. 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

47. 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

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

49. 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

50. 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

51. 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.

52. 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.

53. 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

54. 50. Using a diagram, describe the basic features of an electric series and parallel circuit. Wire

55. 51. What causes charges to move through a circuit? Voltage or difference in electric potential energy

56. 52. Explain Ohm’s Law. What is the formula to calculate resistance? Ohm’s Law describes how voltage, current, and resistance are related. Voltage = Resistance x Current The unit is Ohms Ω

57. 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)

58. 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

59. 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.

60. 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.

61. 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.

62. Solenoid Electromagne t

63. 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.

64. 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

65. 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.

67. 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 = loudLow amplitude = high Frequency – determines pitch High frequency = high pitchLow frequency = low pitch

68. 62. Describe how sound intensity changes with the distance. Give an example. Intensity decreases as the distance increases Ex. Standing behind a fire truck’s siren Intensity increases as the distance decreases Ex. Standing in front of a fire truck’s siren

69. 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.

70. 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.

71. 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.

72. 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.

73. 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.

74. Plane mirror Convex mirror Concave mirror

75. 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

76. 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

78. 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