1. Semester Exam Study Guide- Answer Review
8th Grade

2. 2. What is the basic SI unit of length?
1. An object is in motion if its position changes relative to a ______ ______.
Reference Point
2. What is the basic SI unit of length?
Meter
3. When you know the speed and direction of an object’s motion, you know its ____.
Velocity
4. What is negative accleration? Give an example?
Slowing down- a car approaching a red light

3. 5. A reference point is used for ______.
Determining if something is moving.
6. Look at the graph on page 324. Does the graph show a negative acceleration? No
7. Page 324 graph: What does the line represent in terms of speed and acceleration?
Speed increases; object accelerates.
8. Page 324 graph: What is the acceleration between 0 and 6 seconds?
2m/s2

4. 9. What units should be used when expressing acceleration?
m/s2
10. Changing direction in one way that an object can _________.
accelerate.
11. If an object moves in the same direction at a constant speed for 4 hours, what can you say about its velocity and acceleration?
It did not change

5. 12. Newton’s first law of motion is also called the law of _______.
Inertia
13. Between a bowling ball, beach ball, tennis ball, and badminton birdie..which would have more inertia?
A bowling ball.
14. The force that slows down the movement between objects is _________.
Friction

6. 15. Give an example of increasing friction intentionally.
Throwing sand on an icy driveway
16. Balanced forces do not affect the motion of an object because
They are equal and opposite in direction.
17. What does the law of conservation of momentum state?
Momentum cannot be lost, only transferred.

7. 18. What is the difference between mass and weight?
Weight- measures the gravitational pull by the earth on an object.
19. A 200 kg cart is being accelerated by a tractor at a rate of 4 m/s2. How much force is the tractor putting on the cart?
F = MA
F = 200 X 4 = 800 N
20. Newton’s 3rd law says that for every action force there is a reaction force that ____ and ___.
Equal and oppsite.

8. 21. Which of Newton’s laws relates force, mass, and acceleration in the formula F= ma?
22. One way to increase acceleration of an object is by _____ ____.
Increasing Force
23. A 0.5 kg ball is rolled across the floor with a velocity of 2.5 m/s. What is the ball’s momentum?
Momentum = mass X velocity
Momentum = 0.5 kg X 2.5 m/s
1.25 kg X m/s

9. 24. Why is it possible to throw a 0
24. Why is it possible to throw a 0.15 kg baseball much further than a 7kg bowling ball?
The same force is applied to a lighter object.
25. A speedboat pulls a 60 kg water skier. The force causes the skier to accelerate at 1.5 m/s2. Calculate the net force that causes this acceleration.
F = M X A
F = 60 X 1.5
F = 90

10. 26. How do snowshoes enable a person to walk on deep snow?
Increases the area over which the person’s weight is distributed.
27. What happens to air pressure as elevation increases?
It decreases
28. Water pressure increases as ____ ___.
Depth increases

11. 30. Which principle explains flight?
29. What scientific rule describes why water squirts from a plastic bottle when it is squeezed?
Pascal’s
30. Which principle explains flight?
Bernoulli’s
31. During high winds, the windows in a building may bulge outward because the air pressure inside the building is ___ ____ the air pressure outside the building.
Greater Than

12. 32. What scientific rule states that the buoyant force on an object is equal to the weight of the fluid displaced by the object?
Archimedes
33. A pitcher is able to throw a curve ball partly because of ____ _____.
Bernoulli’s Principle
34. Pascal’s principle states that when force is applied to a confined fluid, the change in pressure is transmitted _________.
Equally to all parts of the fluid

13. 35. What 2 factors does pressure depend on?
Force & Area
36. What must happen for work to be done on an object?
The object must move some distance as a result of a force.
37. Give an example of work being done.
Pushing a child on a swing

14. 38. The mechanical advantage of a machine is the number of times a machine increases ________.
The force exerted on the machine.
39. The mechanical advantage of a machine that changes only the direction of force is _____. 1
40. The ideal mechanical advantage would equal the actual mechanical advantage if there were no loses due to _______.
Friction

15. 41. All machines have a(n) _____ of less than 100%
Efficiency
42. The output work of a machine is 14,000J. If the input work is 17,500 J, the efficiency is _____.
Efficiency = output / input X 100%
Efficiency = 14,000J / 17,500 J
80%

16. 43. Frank does 2,800J of work in climbing a set of stairs
43. Frank does 2,800J of work in climbing a set of stairs. If he does the work in 3 seconds, what is his power output?
Power = Work / Time
Power = 2,800 J / 3 seconds=
933.3

17. 46. The ability to do work is _____.
44. How much work does an elephant do while moving a circus wagon 35 meters with a pulling force of 1,500 N.
Work = Force X Distance
Work = 1,500 N X 35 Meters
52,500
45. A machine makes work easier by multiplying force or __________, or by changing direction.
Distance
46. The ability to do work is _____.
Energy

18. 47. Energy associated with motion is ____ _____.
Kinetic energy
48. Kinetic energy increases as ___________.
Both mass and velocity increase.
49. Give an example of an object that has kinetic energy?
Rolling bowling ball
50. What does the law of conservation of energy state?
No energy is created or destroyed

19. 52. Potential energy that depends on height is _____ ______ _____.
51. A change from one form of energy into another is a(n) ______ ______.
Energy Transformation
52. Potential energy that depends on height is _____ ______ _____.
Gravitational Potential Energy
53. What would always be true of an object possessing a kinetic energy of 0 joules?
It is at rest
54. Which would always be true of an object possessing a potential energy of 0 joules?
It is on the ground

20. 56. A light bulb transforms _____ energy into ____ energy.
55. If an object is at rest, it certainly does not possess this form of energy.
Kinetic
56. A light bulb transforms _____ energy into ____ energy.
Electrical to light
57. A ball thrown into the air has its greatest _____ energy as it reaches its highest point.
Potential

21. 58. As water runs over a waterfall, its ____ energy is transformed into ____ energy.
Potential to kinetic
59. A baseball flying through the air has ____ energy because of its motion and ____ energy because of its position.
Kinetic and potential
60. A large truck and a small car are moving at the same speed. The truck has greater kinetic energy because its _____ is greater.
mass

22. 61. How can moving water be used to produce electricity?
Because most forms of energy can be changed into other forms.
62. The rate at which energy is transferred is called _______.
Power
63. Waves that move the particles of a medium parallel to direction the wave is traveling is ______ ______.
Longitudinal waves

23. 66. Electromagnetic waves can transfer energy without a(n) _____.
64. A disturbance that transfers energy from place to place is called _____.
Wave
65. The distance between 2 corresponding parts of a wave is the _______.
Wavelength
66. Electromagnetic waves can transfer energy without a(n) _____.
Medium
67. Frequency is measured in ______.
hertz

24. 69. Red has the longest ______ of any color of visible light.
68. Which EM waves have the longest wavelengths and lowest frequencies?
Radio waves
69. Red has the longest ______ of any color of visible light.
Wavelength
70. The EM waves with the highest frequencies are called _____ ____.
Gamma Rays
71. The _______ of a mechanical wave is a direct measure of its energy.
amplitude

25. 72. The _______ the wavelength a wave has, the ______ its frequency.
Shorter; higher
73. What is a transverse wave?
A disturbance that transfers energy perpendicular to its medium
74. What is an example of a longitudinal wave?
Sound
75. What is the low point on a transverse wave?
Trough

26. 76. If a person is generating a wave through a medium, what is the person transferring to that medium?
Energy