1. Chapter 2, Section 1: Picturing Motion
Essential Questions
How do motion diagrams represent motion?
How can you use a particle model to represent a moving object?
Chapter 2, Section 2: Where and When?
Essential Questions
What is a coordinate system?
How does the chosen coordinate system affect the sign of objects’ positions?
How are time intervals measured?
What is displacement?
How are motion diagrams helpful in answering questions about an object’s position or displacement?

2. When an object is in motion, its position changes.
Chapter 2, Section 1 & 2
All Kinds of Motion
When an object is in motion, its position changes.
Its position can change in many ways, including
straight line
a circle
back-and-forth vibration
A description of motion relates to place and time.
List and describe several examples of motion from your own experience.
Picturing Motion
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3. Motion Diagrams and Particle Models
A series of images showing the positions of a moving object at equal time intervals is called a motion diagram.
In a particle model, you replace the object or objects of interest with single points.
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Picturing Motion

4. Motion Diagrams and Particle Models
Concepts in Motion
Picturing Motion
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5. The origin is the point at which both variables have the value zero.
Coordinate Systems
A coordinate system tells you the location of the zero point of the variable you are studying and the direction in which the values of the variable increase.
The origin is the point at which both variables have the value zero.
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Where and When?

6. Consider a runner on this coordinate system.
Coordinate Systems
Consider a runner on this coordinate system.
You can indicate how far away an object is from the origin at a particular time by drawing an arrow from the origin to the object.
The two arrows locate the runner’s position at two different times.
Position is the distance and direction from the origin to the object.
Where and When?

7. Position is an example of a vector. It is represented by the symbol x.
Vectors and Scalars
Quantities that have both size (also called magnitude) and direction are called vectors.
Vectors can be represented by arrows of a particular length and pointed in a particular direction.
Position is an example of a vector. It is represented by the symbol x. x1 x2
Where and When?
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8. Vectors and Scalars
A quantity that is just a magnitude (number and unit), without any direction is a scalar.
Examples of scalars:
Time
Distance
Temperature
Is mass a scalar? Explain.
Yes. Mass has a magnitude, but no direction.
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Where and When?

9. The difference between two times is called a time interval.
Time is a Scalar
The difference between two times is called a time interval.
Time intervals are scalars.
The time interval is defined mathematically as follows:
∆ is the Greek letter delta. It is used to represent a change in a quantity.
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Where and When?

10. A change in position is called a displacement.
Displacement is a Vector
A change in position is called a displacement.
Displacement is a vector. It is drawn with its tail at the earlier position and its tip at the later position.
Displacement can be represented mathematically as
∆x = xf
− xi xf xi ∆x
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Where and When?

11. So if A is 5 km, east and B is 2 km, east, then the resultant is
Vector Addition
A vector that represents the sum of two other vectors is called a resultant.
Draw the vectors tip to tail, and the resultant goes from the tail of the first, to the tip of the last.
So if A is 5 km, east and B is 2 km, east, then the resultant is
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Where and When?

12. Vector Addition – You try it:
Vector Computations
Vector Addition – You try it:
If A is 4 km, east and B is 6 km, west, what is A + B?
So R = A + B
R = 2 km, west
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Where and When?

13. If A is 7 km, east and B is 4 km, west, what is A + B?
Vector Addition
Try another one:
If A is 7 km, east and B is 4 km, west, what is A + B?
So R = A + B
R = 3 km, east
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Where and When?

14. How do motion diagrams represent motion?
Review C2 S1
Vocabulary
motion diagram
particle model
Essential Questions
How do motion diagrams represent motion?
How can you use a particle model to represent a moving object?
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Picturing Motion

15. What is a coordinate system?
Review C2 S2
Vocabulary
Essential Questions
What is a coordinate system?
How does the chosen coordinate system affect the sign of objects’ positions?
How are time intervals measured?
What is displacement?
How are motion diagrams helpful in answering questions about an object’s position or displacement?
coordinate system
origin
position
distance
magnitude
vector
scalar
time interval
displacement
resultant
Where and When?
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