1. Ch. 2 Representing Motion

2. 2.1 Picturing Motion
Motion Diagrams
A series of images of a moving object that records its position after each equal time interval
Figures 2-3

3. The Particle Model Use a point to represent the body in motion.
Disregard the arms and legs or the wheels
The point is placed at the center of gravity.
The process is called the particle model.
Creates a simplified version of the object

4. 2.2 Where and When?

5. Coordinate Systems Sets up the beginning of the event
Defines the zero point (origin) or the starting point
Defines the direction of increasing values
Some events require 2 dimensions
x-axis (horizontal) and y-axis (vertical)

6. Locate the object at any time in the event based on the defined coordinate system
Position vector is an arrow that indicates where the object is at a given time from the origin

7. Vectors and Scalars
Scalar quantity- indicated only the magnitude of something
Tells how big or small
Vector quantity- indicated magnitude and also direction of the object.
This book makes the symbol bold faced to represent a vector
Resultant is the sum of the other vectors

8. Time Intervals and Displacements
Displacement-defines the distance and the direction between two positions
Vector quantity
Distance-only indicates how far from the origin
Scalar quantity
Time interval-the time for an event

9. Time on the x-axis and position (displacement) on the y-axis
2.3 Position-Time Graphs
Time on the x-axis and position (displacement) on the y-axis

10. Equivalent Representations
Many different ways to describe motion. Depends upon what you want to find out as to what method you would use.
Words, pictures, motion diagrams, data tables, position-time graphs