1. Graphing Displacement and Velocity

2. Types of Graphs
In Physics 20, you are responsible for being able to make inferences based on graphical data.
The two types of graphs which you will see most commonly are:
Position vs. Time graph
Velocity vs. Time graph

3. Position-Time Graph
This graph depicts an objects position over time.

4. Position-Time Graph
Different position-time graphs tell us different things.
1. Horizontal line: object is at rest. (ie. position does not change over time)
2. Linear: constant speed (velocity)
3. Curved: changing speed (velocity) = acceleration

5. Position-Time Graph
The slope of a position-time graph is equal to the objects velocity.
Always use the largest possible values for rise and run to get a more accurate slope value.

6. Position-Time Graph
Instantaneous Velocity

7. Velocity-Time Graph
Different velocity-time graphs can tell us different things.
1. Horizontal line: object is moving with constant speed (may be 0) (ie. look at y-intercept to determine speed/velocity)
2. Linear: changing speed (velocity), constant acceleration
3. Curved: changing acceleration (not in physics 20).

8. Velocity-Time Graph
The slope of a velocity-time graph is equal to the objects acceleration.

9. Velocity-Time Graph
The “area under the curve” of the velocity-time graph is the objects displacement.

10. One more example….

11. To Summarize…. d vs. t graph v vs. t graph The position of the object
The time
Horizontal line - not moving and the y-intercept is the position
Slope = speed or velocity
The velocity of the object
Horizontal line – constant velocity and the y-intercept is the velocity
Slope = acceleration
Area under the curve = distance/displacement

12. Homework
pg. 3 #6 – 9
pg. 8 #2