1. 1. You must use a reference point to describe an object’s motion.
Do you agree or disagree?
1. You must use a reference point to describe an object’s motion.
2. An object that is accelerating must be speeding up.
Lesson 1 - Now

2. Lesson 1 Reading Guide - KC
Describing Motion
What information do you need to describe the motion of an object?
How are speed, velocity, and acceleration related?
How can a graph help you understand the motion of an object?
Lesson 1 Reading Guide - KC

3. Lesson 1 Reading Guide - Vocab
Describing Motion
motion
reference point
distance
displacement
speed
velocity
acceleration
Lesson 1 Reading Guide - Vocab

4. Motion Motion is the process of changing position.
The starting point you use to describe the motion or the position of an object is called the reference point.
In addition to using a reference point to describe motion, you also need a direction.
Lesson 1-1

5. Name three reference points in this picture you can use to describe the motion of the baseball.

6. Motion (cont.) Distance is the total length of the path traveled.
Displacement is the distance between an initial, or starting, position, and a final position.
Lesson 1-1

7. Motion (cont.)
The distance traveled and the displacement from the game to the vending machine differ.
Lesson 1-1

8. Motion (cont.)
What information do you need to describe an object’s motion?
Hand Raiser
Lesson 1-1

9. Motion (cont.)
What information do you need to describe an object’s motion?
Answer: you need a reference point, a direction, and a distance.
Lesson 1-1

10. Speed
Speed is the distance an object moves divided by the time it took to move that distance.
Speed can be constant or changing.
Average speed is the ratio of the distance an object moves to the time it takes for the object to move that distance.
Lesson 1-2

11. Speed (cont.)
The girl moves with constant speed during the first 4 seconds. The girl’s speed begins to change between seconds 4 and 5.
Explain how her speed is constant from seconds 1-4 and it is changing from 5-7
Lesson 1-2

12. Velocity Velocity is the speed and direction of an object’s motion.
What practical uses are their for velocity?
Storm tracking
Air and sea travel
Lesson 1-3

13. Often, velocity is shown by using an arrow
Often, velocity is shown by using an arrow. The length of the arrow represents the speed of an object, while the direction in which the arrow points represents the direction in which the object is moving.
Lesson 1-3

14. Each segment of the arrow shows the distance and the direction you move in a given unit of time.
Lesson 1-3

15. Because each segment is the same length, you are moving the same distance and in the same direction during each interval of time.
Lesson 1-3

16. Because both your speed and direction of movement are constant, you are moving at a constant velocity.
Answer to #14
Lesson 1-3

17. The velocity of an object changes if the speed changes, the direction changes, or both the speed and the direction change.
Lesson 1-3

18. Velocity (cont.)
Because velocity includes both speed and direction, velocity can change if the speed of an object remains constant.
When either an object’s speed or velocity changes, the object is accelerating.
Acceleration is the measure of how quickly the velocity of an object changes.
Answer 15 and 16
Lesson 1-3

19. Velocity (cont.)
An object moving at a constant speed can have a change in velocity. Explain how to your partner.
Lesson 1-3

20. Velocity (cont.)
An object moving at a constant speed can have a change in velocity. Explain how to your partner.
Answer: because the direction of the object can change which would change the velocity of the object.
Lesson 1-3

21. Calculating Acceleration
Average acceleration can be calculated by using the following equation:
This equation refers only to a change in speed, not direction.
The symbol vf represents final velocity, vi represents initial velocity, and t represents time it takes to make that change in velocity.
Lesson 1-4

22. Calculating Acceleration (cont.)
Lesson 1-4

23. Calculating Acceleration (cont.)
When an object speeds up, its final velocity is greater than its initial velocity.
When an object speeds up, it has positive acceleration.
When an object slows down, the initial velocity is greater than its final velocity.
As an object slows down, it has negative acceleration, or deceleration.
Lesson 1-4

24. Using Graphs to Represent Motion
A displacement-time graph shows an object’s speed and distance from the reference point at any given time.
Lesson 1-5

25. On a displacement-time graph, the x-axis shows the time and the y-axis shows the displacement from a reference point.
Answer 21
Lesson 1-5

26. The line on a displacement-time graph represents the average speed of an object at a particular moment in time.
Lesson 1-5

27. Answer # 22
Lesson 1-5

28. A speed-time graph shows an object’s speed at any given time.
Lesson 1-5

29. On a speed-time graph, the x-axis shows the time, and the y-axis shows the speed of an object.
Answer 32
Lesson 1-5

30. The line on a speed-time graph shows how the speed of an object changes as it moves.
Lesson 1-5

31. Answer 24
Lesson 1-5

32. A description of an object’s motion includes a reference point, a direction from the reference point, and a distance.
Lesson 1 - VS

33. Speed is the distance traveled by an object in a unit of time
Speed is the distance traveled by an object in a unit of time. Velocity includes both speed and direction of motion.
Lesson 1 - VS

34. Acceleration is a change in velocity
Acceleration is a change in velocity. Velocity changes when either the speed, the direction, or both the speed and the direction change.
Lesson 1 - VS

35. Which term refers to the distance between an initial position and a final position?
A. displacement
B. distance
C. motion
D. speed
Lesson 1 – LR1

36. Which is the measure of how quickly the velocity of an object changes?
A. acceleration
B. distance
C. motion
D. speed
Lesson 1 – LR2

37. On a speed-time graph, what does the x-axis show?
A. average speed
B. displacement
C. distance
D. time
Lesson 1 – LR3

38. 1. You must use a reference point to describe an object’s motion.
Do you agree or disagree?
1. You must use a reference point to describe an object’s motion.
2. An object that is accelerating must be speeding up.
Lesson 1 - Now