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. Conceptual Problems (from lab)
Section 1 Displacement and Velocity
Chapter 2
Conceptual Problems (from lab)
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.
A bus travels 280. km south along a straight path with an average velocity of 88. km/hr to the south. The bus stops for 24. minutes. Then it travels 210. km south with an average velocity of 75. km/hr to the south. A) How long does the total trip last? B) What is the average velocity for the total trip?

5. Interpreting Velocity Graphically
Section 1 Displacement and Velocity
Chapter 2
Interpreting Velocity Graphically
If the velocity is constant, the graph of x vs t is a straight line. The slope indicates the velocity.
Object 1: positive velocity
Object 2: zero velocity
Object 3: negative velocity

6. Interpreting Velocity Graphically, continued
Section 1 Displacement and Velocity
Chapter 2
Interpreting Velocity Graphically, continued
Instantaneous velocity
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.
The slope of the velocity-time graph is the average acceleration.

8. Chapter 2 Section Review
Section 1 Displacement and Velocity
Chapter 2
Section Review
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?
Sally travels by car from one city to another. She drives for 30.0 min at 80.0 km/hr, 12.0 min at 105 km/hr and 45.0 min at 40.0 km/hr, and she spends 15.0 min eating lunch and buying gas.
Determine the total distance traveled.
Determine the average speed for the trip.
Graph review wkst