1. Unit 2: Graphical Relationships
Sprayberry
Physics

2. Physics Comp Book UNIT 2: Graphical Relationships
Copy GPS listed on the LTA. Circle the verbs; underline the nouns.
Page Contents
10 Concept Map: Graphical Relationships
11 independent variable / dependent variable
12 x-axis, y-axis
13 slope /
14 Example: Translating Graphs
15 Lab SUMUPS:
* Moving Man Internet Lab
* Running Man

3. Concept Map: Graphical Relationships
Rise
Run
Graphing
Basics
Slope
X-axis
Y-axis
independent & dependent variables
Reading graphs
= velocity!
on position vs. time
on velocity vs. time
= acceleration!
on acceleration vs. time
= zero
(in our class)

4. Graphing Basics: Labeling the axes
Scientists have rules for choosing which variable is graphed on which axis.
On the X-axis (horizontal) is the independent variable
On the Y-axis (vertical) is the dependent variable
Which is the x-axis and which is y-axis?

5. Graphing Basics: indep vs. dep variables
So what are the independent variable and dependent variables?
The independent variable is not affected by the changing dependent variable.
The dependent variable changes as the independent variable.
In other words, the dependent variable DEPENDS on the independent variable.
Independent or dependent?
Time vs. position
Time vs. velocity
Time vs. acceleration
Where would these go on the graph?

6. Graphing Basics: more on variables…
Time (as in a particular moment in time) is TYPICALLY the INDEPENDENT variable.
In this class, if time is graphed, it is on the x-axis.
Think about it: nothing stops time.
Time doesn’t change with speed; speed changes with time.
Independent or dependent?
Time vs. position
Time vs. velocity
Time vs. acceleration
Where would these go on the graph?

7. Frayer Models for: x, y axis & independent and dependent variables
Picture:
Definition:
How to remember:
Examples:

8. Graphing Basics: Slope
The slope of a line describes its steepness. It is the ratio of the vertical change (called the rise) to the horizontal change (called the run).
slope = rise vertical change run horizontal change
Let’s look at the slope of this line:
We can use any two points on the line (the slope of a line is constant).
What is the rise?
What is the run?

9. Finding slope --practice
Another example:
Find the slope—
slope = rise vertical change run horizontal change

10. Use a DISTANCE/TIME GRAPH Steeper the slope = faster the speed
GRAPHING MOTION
Use a DISTANCE/TIME GRAPH
-Time = X axis
-Distance = Y axis
A graph of constant speed will represent the motion with a straight line
To show two constant speeds which are different, you use SLOPE = steepness of the line = speed
Steeper the slope = faster the speed

11. Constant Versus Changing Speed
time
time
CONSTANT SPEED
CHANGING SPEED

12. A graph of changing speed will have a zig-zag or curved line
GRAPHING MOTION
A graph of changing speed will have a zig-zag or curved line

13. Putting it all together
FASTEST CONSTANT SPEED
DISTANCE
SLOWER CONSTANT SPEED
What is the slope of this part of the line?
CHANGING SPEED
TIME

14. Putting it all together
What is the average speed (slope) during the 10 min to 20 min period?
1000
600
Change in distance = = 600m
Amount of time = = 10 min
200
Avg. Speed = change in distance (600 m)
Amount of time (10 min) 10 20 30
= 60 m/min

15. Frayer for Slope Picture: Definition: How to calculate:
What to remember:

16. What does slope mean?