1. How to Use This Presentation
To View the presentation as a slideshow with effects
select “View” on the menu bar and click on “Slide Show.”
To advance through the presentation, click the right-arrow key or the space bar.
From the resources slide, click on any resource to see a presentation for that resource.
From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation.
You may exit the slide show at any time by pressing the Esc key.

2. Resources Chapter Presentation Bellringers Image Bank
Standards Assessment
Math Focus
Visual Concepts

3. Chapter 12 Table of Contents Section 1 Measuring Motion
Matter in Motion
Table of Contents
Section 1 Measuring Motion
Section 2 What Is a Force?
Section 3 Friction: A Force That Opposes Motion

4. Chapter 12
Section 1 Measuring Motion
Bellringer
Describe the location of a favorite place, using a reference point and reference directions. For example, “The library is at the corner of Madison Street and Monroe Street. It is two blocks west of the school and four blocks north of the bus stop.”
Write your response in your Science Journal.

5. Chapter 12 What You Will Learn
Section 1 Measuring Motion
What You Will Learn
Properties used to describe the motion of an object include a reference point, direction, speed, velocity, and acceleration.
Average speed can be calculated by dividing total distance by total time.
A change in velocity is due to a change in speed, direction, or both.
Speed and acceleration can be represented on graphs.

6. Motion and Reference Points
Chapter 12
Section 1 Measuring Motion
Motion and Reference Points
An object is in motion if it changes position over time in relation to a reference point.
A reference point is any object that appears to stay in place.
Features on Earth’s surface are often used as standard reference points.

7. Motion and Reference Points, continued
Chapter 12
Section 1 Measuring Motion
Motion and Reference Points, continued
Reference directions—such as north, south, east, west, up, or down—can be used to describe the direction of an object’s motion.
A grid can be used to describe motion in a two-dimensional system.

8. Chapter 12
Section 1 Measuring Motion
Average Speed
The speed of an object is the rate at which the object moves.
The speed of an object is rarely constant. So, it is useful to find the average speed of an object.

9. Average Speed, continued
Chapter 12
Section 1 Measuring Motion
Average Speed, continued
Average speed is the total distance traveled divided by the total time taken.
A graph of position versus time can show an object’s speed. On a graph of position versus time, the slope of the line is equal to the speed of the object.

10. Velocity: Direction Matters
Chapter 12
Section 1 Measuring Motion
Velocity: Direction Matters
Velocity is the speed of an object in a particular direction.
Velocity and speed do not have the same meaning.
Velocity must include a direction.

11. Velocity: Direction Matters, continued
Chapter 12
Section 1 Measuring Motion
Velocity: Direction Matters, continued
The velocity of an object is constant only if the speed and direction of the object do not change. So, constant velocity is always motion along a straight line.
The velocity of an object changes if the object’s speed, direction, or both change.

12. Chapter 12
Matter in Motion
Velocity

13. Chapter 12
Section 1 Measuring Motion
Acceleration
Acceleration is the rate at which velocity changes over time.
An object can accelerate by changing speed, direction, or both.
The units for acceleration are the units for velocity divided by a unit for time, usually meters per second per second, or (m/s)/s, which is also written as m/s2.

14. Chapter 12
Matter in Motion
Acceleration

15. Acceleration, continued
Chapter 12
Section 1 Measuring Motion
Acceleration, continued
Centripetal acceleration occurs when an object moves at a constant speed in circular motion.
A graph of speed versus time can show positive acceleration, no acceleration, and negative acceleration.

16. Chapter 12
Matter in Motion

17. Chapter 12
Section 2 What Is a Force?
Bellringer
A force is a push or a pull on an object. Imagine that you are trying to push a box up a ramp. Describe as many forces (pushes and pulls) as you can in that situation. Be sure to include the direction of each force (push or pull) in your description.
Write your answers in your Science Journal.

18. Chapter 12 What You Will Learn
Section 2 What Is a Force?
What You Will Learn
A force is a push or a pull that acts on an object. Forces have magnitude and direction.
Net force is the combined effect of two or more forces acting on an object.
Balanced forces do not cause changes in motion.
Unbalanced forces cause changes in an object’s velocity.

19. Forces Acting on Objects
Chapter 12
Section 2 What Is a Force?
Forces Acting on Objects
A force is a push or a pull exerted on an object in order to change the motion of the object.
All forces have two properties: direction and magnitude, or size.
Forces can cause acceleration.

20. Forces Acting on Objects, continued
Chapter 12
Section 2 What Is a Force?
Forces Acting on Objects, continued
Forces always act on objects. For any push to occur, something has to receive the push.
A newton (N) is the SI unit used to describe the magnitude, or size, of a force.
A force can act on an object without causing the object to move.

21. Chapter 12
Matter in Motion
Force

22. Combined Effect of Forces
Chapter 12
Section 2 What Is a Force?
Combined Effect of Forces
The net force is the combination of all the forces acting on an object.
When forces act in the same direction, you add the forces to determine the net force.
When two forces act in opposite directions, you subtract the smaller force from the larger force to determine the net force.

23. Chapter 12
Matter in Motion

24. Balanced Forces: No Change in Motion
Chapter 12
Section 2 What Is a Force?
Balanced Forces: No Change in Motion
When the forces on an object produce a net force of 0 N, the forces are balanced.
Balanced forces do not cause a change in the motion of an object.

25. Balanced Forces: No Change in Motion, continued
Chapter 12
Section 2 What Is a Force?
Balanced Forces: No Change in Motion, continued
Objects that are not moving and have balanced forces acting on them are called static objects.
Tension and compression are two forces that often act on static objects.

26. Balanced Forces: No Change in Motion, continued
Chapter 12
Section 2 What Is a Force?
Balanced Forces: No Change in Motion, continued
Tension is a force that is exerted when matter is pulled or stretched.
Compression is a force that is exerted when matter is pushed or squeezed.

27. Unbalanced Forces: Velocity Changes
Chapter 12
Section 2 What Is a Force?
Unbalanced Forces: Velocity Changes
When the net force on an object is not 0 N, the forces on the object are unbalanced.
Unbalanced forces cause a change in the velocity of an object.

28. Unbalanced Forces: Velocity Changes, continued
Chapter 12
Section 2 What Is a Force?
Unbalanced Forces: Velocity Changes, continued
Unbalanced forces are needed to cause static objects to start moving.
Objects do not always move in the direction of the unbalanced force.

29. Section 3 Friction: A Force That Opposes Motion
Chapter 12
Bellringer
Imagine that you are trying to push a heavy desk across the floor. There are two opposing forces on the desk: the force you apply, and the force of friction between the desk and the floor. What will happen if the force of friction is the same magnitude as the force that you apply? What will happen if the force that you apply is greater than the force of friction?
Write your answers in your Science Journal.

30. Chapter 12 What You Will Learn
Section 3 Friction: A Force That Opposes Motion
Chapter 12
What You Will Learn
The magnitude of the force of friction can vary.
Kinetic friction is a force that, when unbalanced, can change the velocity of a moving object.
Static friction balances an applied force and can prevent motion.
Friction can be both harmful and helpful.

31. Chapter 12 The Source of Friction
Section 3 Friction: A Force That Opposes Motion
Chapter 12
The Source of Friction
When the hills and valleys of one surface stick to the hills and valleys of another surface, friction is created.
Friction is a force that opposes motion between two surfaces that are touching.

32. The Source of Friction, continued
Section 3 Friction: A Force That Opposes Motion
Chapter 12
The Source of Friction, continued
As the force pushing surfaces together increases, the friction between the surfaces increases.
Friction is usually greater between materials that have rough surfaces than it is between materials that have smooth surfaces.

33. Chapter 12
Matter in Motion

34. Chapter 12 Types of Friction
Section 3 Friction: A Force That Opposes Motion
Chapter 12
Types of Friction
There are two types of friction: kinetic friction and static friction.
Kinetic friction is friction between moving surfaces.
The force of sliding kinetic friction is greater than the force of rolling kinetic friction.

35. Types of Friction, continued
Section 3 Friction: A Force That Opposes Motion
Chapter 12
Types of Friction, continued
Static friction can balance an applied force and can prevent changes in motion.
Some static objects do not move because the force of static friction balances the other forces acting on the object.

36. Chapter 12
Matter in Motion

37. Friction: Harmful and Helpful
Section 3 Friction: A Force That Opposes Motion
Chapter 12
Friction: Harmful and Helpful
Because friction can be both harmful and helpful, sometimes it should be decreased and sometimes it should be increased.
Lubricants are substances that are put on surfaces to decrease friction between the surfaces. Some examples of lubricants include motor oil, wax, and grease.

38. Friction: Harmful and Helpful, continued
Section 3 Friction: A Force That Opposes Motion
Chapter 12
Friction: Harmful and Helpful, continued
Harmful friction can be decreased by using lubricants or by smoothing the surfaces that rub against each other.
Helpful friction can be increased by making the surfaces that rub against each other rougher or by increasing the force pushing surfaces together.

39. Chapter 12
Matter in Motion
Concept Map
Use the terms below to complete the concept map on the next slide.
speed
time
velocity
motion
acceleration

40. Chapter 12
Matter in Motion
Concept Map

41. Chapter 12
Matter in Motion
Concept Map

42. Chapter 12 End of Chapter 12 Show
Matter in Motion
End of Chapter 12 Show

43. Chapter 12
Standards Assessment
1. Which of the following words means “stress that happens when forces act to stretch an object”?
A. drive
B. tension
C. torque
D. energy

44. Chapter 12
Standards Assessment
1. Which of the following words means “stress that happens when forces act to stretch an object”?
A. drive
B. tension
C. torque
D. energy

45. Chapter 12
Standards Assessment
2. Which of the following words is the closest in meaning to the word involve?
A. include
B. ascertain
C. believe
D. accompany

46. Chapter 12
Standards Assessment
2. Which of the following words is the closest in meaning to the word involve?
A. include
B. ascertain
C. believe
D. accompany

47. Chapter 12
Standards Assessment
3. In the sentence “By interpreting the data in the graph, the scientist learned that the speed of the car had been constant,” what does the word interpreting mean?
A. figuring out the meaning of
B. interacting with
C. disposing of
D. identifying the parts of

48. Chapter 12
Standards Assessment
3. In the sentence “By interpreting the data in the graph, the scientist learned that the speed of the car had been constant,” what does the word interpreting mean?
A. figuring out the meaning of
B. interacting with
C. disposing of
D. identifying the parts of

49. Chapter 12
Standards Assessment
4. Which of the following sets of words best completes the following sentence: “Position _____ relation to a reference point and a set of references directions.”
A. defines with
B. was defined of
C. is defined in
D. definition by

50. Chapter 12
Standards Assessment
4. Which of the following sets of words best completes the following sentence: “Position _____ relation to a reference point and a set of references directions.”
A. defines with
B. was defined of
C. is defined in
D. definition by

51. Chapter 12
Standards Assessment
5. Which of the following is the noun form of the verb specify?
A. specific
B. specifically
C. specified
D. specification

52. Chapter 12
Standards Assessment
5. Which of the following is the noun form of the verb specify?
A. specific
B. specifically
C. specified
D. specification

53. Chapter 12
Standards Assessment
6. The rate at which an object moves is its speed. If a horse walked 50 m in 68 s, cantered 150 m in 35 s, and galloped 300 m in 22 s, what would its average speed be?
A m/s
B. 4 m/s
C m/s
D. 40 m/s

54. Chapter 12
Standards Assessment
6. The rate at which an object moves is its speed. If a horse walked 50 m in 68 s, cantered 150 m in 35 s, and galloped 300 m in 22 s, what would its average speed be?
A m/s
B. 4 m/s
C m/s
D. 40 m/s

55. Chapter 12 7. What is the difference between speed and velocity?
Standards Assessment
7. What is the difference between speed and velocity?
A. Velocity is expressed in m/s. Speed is expressed in m/s2.
B. Speed involves a constant rate of acceleration, and velocity does not.
C. Speed is measured by time and distance, but velocity also includes direction.
D. Velocity involves moving in a direction in a straight line, and speed does not.

56. Chapter 12 7. What is the difference between speed and velocity?
Standards Assessment
7. What is the difference between speed and velocity?
A. Velocity is expressed in m/s. Speed is expressed in m/s2.
B. Speed involves a constant rate of acceleration, and velocity does not.
C. Speed is measured by time and distance, but velocity also includes direction.
D. Velocity involves moving in a direction in a straight line, and speed does not.

57. Chapter 12
Standards Assessment
8. A teenager pulls a rope to the left with a force of 12 N. A child pulls on the other end of the rope to the right with a force of 7 N. The child’s friend adds a force of 8 N, also pulling to the right. What will happen?
A. The net force will be 3 N to the right.
B. The net force will be 15 N to the left.
C. The net force will be 12 N to the right.
D. The net force will be 27 N to the left.

58. Chapter 12
Standards Assessment
8. A teenager pulls a rope to the left with a force of 12 N. A child pulls on the other end of the rope to the right with a force of 7 N. The child’s friend adds a force of 8 N, also pulling to the right. What will happen?
A. The net force will be 3 N to the right.
B. The net force will be 15 N to the left.
C. The net force will be 12 N to the right.
D. The net force will be 27 N to the left.

59. Chapter 12
Standards Assessment
9. Which of the following are forces that act on a person leaning against a pole at a bus stop?
A. gravity and newtons
B. tension and weight
C. tension and kinetic friction
D. gravity and static friction

60. Chapter 12
Standards Assessment
9. Which of the following are forces that act on a person leaning against a pole at a bus stop?
A. gravity and newtons
B. tension and weight
C. tension and kinetic friction
D. gravity and static friction

61. Chapter 12 Use the graph below to answer the next question.
Standards Assessment
Use the graph below to answer the next question.

62. Chapter 12
Standards Assessment
10. The graph above shows a person walking. Which of the following sentences best describes the walker’s speed?
A. She travels an average of 10 m/s.
B. She travels an average of 4 m/s.
C. Her rate of speed decreases after 5 s.
D. Her rate of speed increases after 5 s.

63. Chapter 12
Standards Assessment
10. The graph above shows a person walking. Which of the following sentences best describes the walker’s speed?
A. She travels an average of 10 m/s.
B. She travels an average of 4 m/s.
C. Her rate of speed decreases after 5 s.
D. Her rate of speed increases after 5 s.

64. Chapter 12
Standards Assessment
11. All forces are measured by their direction and their size. Another term for the size of a force is
A. circumference.
B. magnitude.
C. cumulative force.
D. velocity.

65. Chapter 12
Standards Assessment
11. All forces are measured by their direction and their size. Another term for the size of a force is
A. circumference.
B. magnitude.
C. cumulative force.
D. velocity.

66. Chapter 12
Standards Assessment
12. What is matter?
A. solid things that you can see and touch
B. anything contained in a gravitational field
C. anything that has mass and volume
D. things with a definite shape and volume

67. Chapter 12
Standards Assessment
12. What is matter?
A. solid things that you can see and touch
B. anything contained in a gravitational field
C. anything that has mass and volume
D. things with a definite shape and volume

68. Chapter 12
Standards Assessment
13. Which of the following holds the electrons of an atom around the atom’s nucleus?
A. strong force
B. electromagnetic force
C. weak force
D. gravitational force

69. Chapter 12
Standards Assessment
13. Which of the following holds the electrons of an atom around the atom’s nucleus?
A. strong force
B. electromagnetic force
C. weak force
D. gravitational force

70. Chapter 12 14. What is the function of tendons in the human body?
Standards Assessment
14. What is the function of tendons in the human body?
A. They coordinate muscle groups.
B. They provide support for the body.
C. They connect two muscles.
D. They attach muscle to bone.

71. Chapter 12 14. What is the function of tendons in the human body?
Standards Assessment
14. What is the function of tendons in the human body?
A. They coordinate muscle groups.
B. They provide support for the body.
C. They connect two muscles.
D. They attach muscle to bone.

72. Chapter 12
Standards Assessment
15. The diagram below shows a class-3 lever. Which of the following is an example of a class-3 lever?
A. a pencil
B. a wheelbarrow
C. a see saw
D. a stapler

73. Chapter 12
Standards Assessment
15. The diagram below shows a class-3 lever. Which of the following is an example of a class-3 lever?
A. a pencil
B. a wheelbarrow
C. a see saw
D. a stapler

74. Chapter 12