8 th Grade Science Final Exam Review. 1. What are the tests used to identify a mineral? Streak – color of a mineral’s powder. Fracture – splitting a mineral.

8th Grade Science Final Exam Review

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/volumeHardness – Moh’s Scale (Talc = 1: Diamond

= 10)

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.

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

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

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

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

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

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

9. Describe the Richter Scale in terms of values and how it’s measured.

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

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

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

13. List some ways that mountains can form?

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

15. How is volcanic ash formed?

16. Why do volcanoes form where plates collide?

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

18. How does a caldera form?

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

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?

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

22. Explain why reference points that are stationary are usually chosen to determine whether an object is in motion.

23. How do you calculate an object’s speed?

24. Describe what velocity is.

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

Time

Dis

tanc

e

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

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

28. Describe what a force is.

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

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

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.

32. State Newton’s Three Laws of Motion and give an example of each1st 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.

32. State Newton’s 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/massEx: a cart goes faster when something falls out

32. State Newton’s 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

33. Explain how momentum is determined and conserved.Momentum = Mass x VelocityLaw 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

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.

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

supplies centripetal force.

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 DistanceNOT WORK WORK

37. Define powerPower equals the amount of work done on

an object in a unit of time Power = Force x Distance/Time

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 forceChanging Force Changing Distance Changing Direction

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%

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/heightThe ramp with the smallest mechanical advantage is

the steepest

Wedges = length of the wedge/width of the wedgeThe longer and thinner a wedge is, the greater the

mechanical advantage

Screws = length around threads/length of screwThe closer together the threads of a screw are, the greater the mechanical advantage

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

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

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

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

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

45. Name and describe the two basic types of energy. Kinetic Energy: the energy that an object

has due to its motionPotential Energy: the energy an object has

because of its position or shape

46. What are the six forms of energy? Give an example of each.Mechanical energy: ex. Falling basketball and

moving carNuclear energy: ex.nuclear power plantThermal energy: ex. A heated pot of water at

75 degrees has more thermal energy than the same water at 30 degrees

Electrical energy: ex. lightningElectromagnetic energy: ex. microwaves and

x-raysChemical energy: ex. bonds are broken in your

cells & release energy for your body to use

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.

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.

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

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

Wire Wire

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

energy

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 CurrentThe unit is Ohms Ω

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)

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 magnetsmagnets, when freely swinging, one end

always points north

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.

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.

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.

Solenoid

Electromagnet

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.

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

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.

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

waveHigh amplitude = loud Low amplitude = high Frequency – determines pitch High frequency = high pitch Low frequency =

low pitch

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 sirenIntensity increases as the distance

decreasesEx. Standing in front of a fire truck’s siren

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.

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.

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.

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.

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.

Plane mirror

Convex mirror

Concave mirror

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

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

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