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

3. Lesson 1-1 A.Motion 1.Motion is the process of changing position. 2.The starting point used to describe the motion or position of an object is called the reference point. Motion

4. Lesson 1-1 3.Distance is the total length of your path of motion. 4.The distance between your final position and your starting position is displacement. 5.A complete description of motion includes a(n) reference point, your displacement, and your direction. Motion (cont.)

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

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

7. Lesson 1-2 B.Speed 1.Speed is the distance an object moves divided by the time it took to move that distance. 2.Speed can be constant or changing. Speed

8. a.A constant speed is unchanging because the distance traveled per unit of time remains the same. b.Speed is changing when the distance traveled per unit of time does not remain the same. c.Average speed is the ratio of the distance moved and the time it took to move that distance.

9. Lesson 1-2 The girl moves with constant speed during the first 4 seconds. The girl’s speed begins to change between seconds 4 and 5. Speed (cont.)

10. Lesson 1-3 C.Velocity 1.The speed and direction of an object’s motion is the velocity of the object. Velocity velocity from Latin velocitatem, means “swiftness or speed”

11. Lesson 1-3 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.

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

13. Lesson 1-3 2.Velocity is often represented by using a(n) arrow. a.The total length of the arrow shows speed. b.The direction of the arrow shows the direction the object moves. Velocity (cont.)

14. 3.When an object’s speed and direction remain the same, the object has constant velocity. 4.Velocity changes when the speed or the direction of the motion of the object changes. 5.The measure of how quickly an object’s velocity changes are called acceleration.

15. Lesson 1-3 Velocity (cont.) Can an object traveling at a constant speed have a changing velocity? Why or why not?

16. Lesson 1-4 D.Calculating Acceleration 1.Acceleration can be calculated by dividing the change in velocity by the time it took for the velocity to change. Calculating Acceleration

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

18. Lesson 1-4 Calculating Acceleration (cont.) How does acceleration differ from velocity?

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

20. Lesson 1-5 E.Using Graphs to Represent Motion 1.A(n) displacement-time graph shows time on the x-axis and displacement from a(n) reference point on the y-axis.

21. Lesson 1-5 a.A line on this type of graph represents average speed. b.The line does not show the actual path of motion.

22. Lesson 1-5

23. 2.A(n) speed-time graph shows time on the x-axis and speed on the y-axis.

24. Lesson 1-5 a.A point on the line on this type of graph represents the speed of the object at that time.

25. b.A(n) horizontal line at y = 0 on a displacement-time graph or a speed-time graph shows that the object is at rest. c.The term constant speed means average speed.

26. Lesson 1-5

27. Using Graphs to Represent Motion (cont.) How can a graph help you understand an object’s motion?

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

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

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