1. Section 1 – pg 338 Describing Motion
Chapter 9
Section 1 – pg 338
Describing Motion

2. Pg 339
Motion
An object is in motion if its distance from another object is changing

3. Pg 339
Reference Points
Reference Point: a place or object used for comparison to determine if something is in motion
Indicate a change in position by using plus and negative signs
IE: 5 feet ahead (+5) 5 feet behind (-5)

4. Pg 340
Relative Motion
Depending on your reference point you may or may not be moving
Sitting in chair reading book:
If your chair is the reference point then you are not moving
If the sun is your reference point then you are moving quite fast

5. Distance and Displacement
Pg 340
Distance and Displacement
Distance: the length of a path between two points
The total length of the actual path between two points
Displacement: the length and direction that an object has moved from its starting point
The length and direction of a straight line between starting and ending points

6. Vector: a quantity that consists of both a magnitude and a direction
Displacement, acceleration, velocity, force
Vectors are shown graphically by using an arrow
The length of the arrow represents the vector’s magnitude
The direction of the arrow indicates the direction of the vector
Pg 341

7. Chapter 9 Section 1 Homework Pg 341

8. 1A. How do you know if an object is moving?

9. 1B. Why is it important to know if your reference point is moving?

10. 1C. Suppose you are riding in a car
1C. Suppose you are riding in a car. Describe your motion relative to the car, to the road, and to the sun.

11. 2A. What is displacement?

12. 2B. How are distance and displacement similar? How are they different?

13. 2C. An object moves 3 cm to the right, then 6 cm to the left, then 8 cm to the right. What is the object’s final displacement from its origin?
3 cm
6 cm
8 cm