1. Friday, 9/19 Pick handout from Physics bin Pick handout from Physics bin We are taking notes today…take out your notebook/paper and something to write with. We are taking notes today…take out your notebook/paper and something to write with. In your notes respond to the following (3 minutes): In your notes respond to the following (3 minutes): 1. We have talked about velocity and its components (distance and time). Use your drawing skills to describe velocity without numbers. 2. We have talked about acceleration and its components (change in velocity and time). Use your drawing skills to describe acceleration.

2. Interpreting Motion Graphs

3. Two Types of Graphs Position time graphs Position time graphs Velocity time graphs Velocity time graphs

4. Position vs. time graphs The slope of the graph is equal to the velocity The slope of the graph is equal to the velocity If the d/t graph is a straight line (no curve) then the velocity is constant. If the d/t graph is a straight line (no curve) then the velocity is constant. Reference Point…. Reference Point….

5. Position vs. time graphs A line with a positive slope indicates positive velocity and the object is moving away from the reference point A line with a positive slope indicates positive velocity and the object is moving away from the reference point A line with a negative slope indicates negative velocity and the object is moving towards the reference point. A line with a negative slope indicates negative velocity and the object is moving towards the reference point.

6. Position vs. time graphs If the line is horizontal (no slope) then the object is stationary (no velocity) If the line is horizontal (no slope) then the object is stationary (no velocity)

7. If the object is accelerating, the velocity is changing If the object is accelerating, the velocity is changing p/t graph will no longer be a straight line, but will have a changing slope, resulting in a curve. p/t graph will no longer be a straight line, but will have a changing slope, resulting in a curve. Position vs. time graphs Accelerated Motion

8. Position vs. time graphs Concave “Up like a cup”…the acceleration is positive Concave “Up like a cup”…the acceleration is positive Slowing down towards Speeding up away

9. Concave “Down like a frown”…the acceleration is negative Concave “Down like a frown”…the acceleration is negative Position vs. time graphs Slowing down awaySpeeding up towards

10. The slope is equal to the acceleration. The slope is equal to the acceleration. Velocity vs. time graphs

11. Positive velocity indicates the object is moving away from the reference point Positive velocity indicates the object is moving away from the reference point The x axis means v=0 The x axis means v=0 Green is slower, getting closer to zero. Green is slower, getting closer to zero. Purple is speeding up, moving farther from the x axis. Purple is speeding up, moving farther from the x axis.

12. Negative velocity indicates the object is moving toward the reference point. Negative velocity indicates the object is moving toward the reference point. Velocity vs. time graphs

13. Velocity vs. time graphs (Acceleration) When the slope is zero: When the slope is zero: –horizontal line – velocity is constant –acceleration is zero

14. Velocity vs. time graphs When the slope of the graph is positive: When the slope of the graph is positive: –the acceleration is positive

15. Velocity vs. time graphs When the slope of the graph is negative: When the slope of the graph is negative: – the acceleration is negative

16. We cannot determine where an object’s position from a v/t graph, only its change in position. We cannot determine where an object’s position from a v/t graph, only its change in position. Velocity vs. time graphs