1. Chapter 2 Velocity and Speed
Section 1 Displacement and Velocity
Chapter 2
Velocity and Speed
Velocity describes motion with both direction and magnitude (a numerical value).
Speed has no direction, only magnitude.
Average speed is equal to the total distance traveled divided by the time interval.

2. displacement = final position – initial position
Section 1 Displacement and Velocity
Chapter 2
Displacement
Displacement is a change in position.
Displacement is not always equal to the distance traveled.
The SI unit of displacement is the meter, m.
Dx = xf – xi
displacement = final position – initial position

3. Chapter 2 Average Velocity
Section 1 Displacement and Velocity
Chapter 2
Average Velocity
Average velocity is the total displacement divided by the time interval during which the displacement occurred.
In SI, the unit of velocity is meters per second, abbreviated as m/s.

4. Chapter 2 Conceptual Problems
Section 1 Displacement and Velocity
Chapter 2
Conceptual Problems
A book is moved once around the edge of a tabletop with dimensions 1.75 m x 2.25 m. If the book ends up at its initial position, what is its displacement? If it completes its motion in 23 s, what is its average velocity? What is its average speed?
Car A travels from New York to Miami at a speed of 25 m/s. Car B travels from New York to Chicago, also at a speed of 25 m/s. Are the velocities of the cars equal? Explain.

5. Interpreting Velocity Graphically
Section 1 Displacement and Velocity
Chapter 2
Interpreting Velocity Graphically
For any position-time graph, we can determine the average velocity by drawing a straight line between any two points on the graph.
If the velocity is constant, the graph of position versus time is a straight line. The slope indicates the velocity.
Object 1: positive slope = positive velocity
Object 2: zero slope= zero velocity
Object 3: negative slope = negative velocity

6. Interpreting Velocity Graphically, continued
Section 1 Displacement and Velocity
Chapter 2
Interpreting Velocity Graphically, continued
The instantaneous velocity is the velocity of an object at some instant or at a specific point in the object’s path.
The instantaneous velocity at a given time can be determined by calculating the slope of the tangent line.

7. Chapter 2 Changes in Velocity
Section 2 Acceleration
Chapter 2
Changes in Velocity
Acceleration is the rate at which velocity changes over time.
An object accelerates if its speed, direction, or both change.

8. Changes in Velocity, continued
Section 2 Acceleration
Chapter 2
Changes in Velocity, continued
The slope of the velocity-time graph is the average acceleration.
A: slope of tangent line is positive
acceleration is positive
B: Velocity is constant, there is
no acceleration
C : slope of tangent line is
acceleration is negative

9. Chapter 2 Section Review Section 1 Displacement and Velocity
Pg 44 #1, 4, 6
Pg 47 #3, 6
Pg 49 #1, 4, 5
Pg 68 #2, 3, 8, 10, 17
Runaway Train
If a passenger train is traveling on a straight track with a negative velocity and a positive acceleration, is it speeding up or slowing down?
Hike-and-Bike Trail
When Laura is out for a ride, she slows down on her bike as she approaches a group of hikers on a trail. Explain how her acceleration can be positive even when her speed is decreasing.