1. Cornell Notes 2-5 Graphing Motion
February 19, 2016
Page 135 & 137

2. Linear and Non-Linear Graphs
Linear graphs go in a straight line.
They represent relationships with the formula y=kx
k is the slope of the line. You can figure out slope by dividing change in y over change in x
(10-5)/(2-1)=5/1=5

3. Non-Linear Graphs Non-linear graphs go in curves
They usually have formulas like y=kx2

5. The Rectangle Method
You can use the rectangle method to make predictions.
Just find the key term on the axis, draw a straight line up to the graph, and another straight line to the other axis.
If you need to, you can extend the graph in either direction to help make your prediction

6. Position vs Time Graphs
In a position vs time graph, time is on the x and position on the y.

7. Speed vs Time Graphs
In a Speed vs time graph, time is on the x and speed on the y.

8. When Something is Not Moving
PvT is a Horizontal Line
SvT is a Horizontal Line at 0
Car isn’t moving, so its speed is 0 m/s
Car stays at 5 m

9. When Something is Moving at a Constant Speed
PvT is a Straight Line
SvT is a Horizontal Line
Car moves 2 m every second!
Car’s speed is 2 m/s

10. When Something is Moving Backwards at a Constant Speed
PvT is a Straight Line Going Down
SvT is a Horizontal Line
Car moves 2 m every second, but backwards!
Car’s speed is 2 m/s

11. Speed vs Speed Faster Objects Have Steeper Slopes
Faster Objects Are Higher Up
2 m/s
2 m/s
1 m/s
1 m/s

12. Changing Speeds (Speeding Up)
PvT Curves!
At Constant Acceleration, SvT is a Straight Line
Slope Gets Steeper!
Speed is increasing by 1 m/s every second

13. Changing Speeds, Slowing Down
PvT Curves
SvT is Now Going Backwards
Car moving 1 m/s slower every second
Still moving forward, but slower every second

14. Slopes on PvT Graphs
The slope on a PvT graph shows the speed of the object.
To calculate slope, do the following
Pick two points on the graph
Subtract the y-values of the points, the point on the right going first (y2-y1)
Subtract the x-values of the points, the point on the right going first (x2-x1)
Divide the y’s by the x’s (Rise over run)

15. Example (120 - 60)  (80 - 40) = 60  40 = 1.5 cm/s Y Goes Up 20
X Goes Up 40
( )  ( ) = 60  40 = 1.5 cm/s

16. Quick Summary for PvT’s
If the line is horizontal, then the object graphed is not moving
If the line is linear, then the object graphed I moving at a constant speed
If the line is non-linear, then the object’s speed is changing
The slope of a PvT graph is the object’s speed
For constant speed, objects with greater speeds have steeper slopes

17. Quick Summary for SvT’s
If the line is at zero, then the object graphed is not moving
If the line is horizontal, then the object graphed is moving at a constant speed
If the line is straight, then the object’s speed is changing at a constant rate

18. Story Time!