1. Chapter 3 - Motion

2. Unit Objectives Distinguish between distance and displacement.
Calculate the average speed of an object.
Explain the difference between speed and velocity.
Write equations for the displacement and velocity of an object over time.
Recognize and draw graphs of an objects displacement and velocity verses time.
Describe how acceleration, time and velocity are related.
Explain how positive and negative acceleration affect motion.
Interpret motion diagrams
Explain how forces and motion are related.
Compare and contrast static friction and sliding friction.
Describe the effects of air resistance on falling objects.

3. 3.1 Notes - Motion
With Lecture Tutorial

4. Today’s Objectives
Distinguish between distance and displacement.

5. Physics of Motion
Mechanics = the study of the motion of objects (physics of motion)
Kinematics = using words to describe the motion of objects
Used to develop models that describe the motion of real-world objects

6. New Vocabulary
Scalar quantity = fully described by a magnitude (or numerical value) alone.
Vector quantity = fully described by both a magnitude and a direction.
Khan Academy Video

7. Examples Quantity Category a. 5 m b. 30 m/sec, East c. 5 mi., North
d degrees Celsius
e bytes
f Calories
Scalar
Vector
Vector
Scalar
Scalar
Scalar

8. Motion Occurs when an object changes position
Position depends on a reference frame

9. Distance The length of the path the object travels Scalar quantity
Physical quality
Does not have direction
Not a vector
refers to "how much ground an object has covered" during its motion.

10. Displacement
Distance & direction of an object’s final position from its original
Size & Direction
A Vector
refers to "how far out of place an object is"
it is the object's overall change in position.

11. Distance vs. Displacement

12. Example Total Distance = _____ Total Displacement = _____
A physics teacher walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North.
12 m
Total Distance = _____
Total Displacement = _____
0 m

13. Example 2 Total Distance = _____ Total Displacement = _____ 420 m
The position of a cross-country skier at various times.
At each of the indicated times, the skier turns around and reverses the direction of travel.
In other words, the skier moves from A to B to C to D.
420 m
Total Distance = _____
Total Displacement = _____
140 m, right

14. Example 3 Total Distance = _____ Total Displacement = _____ 95 yds
As a final example, consider a football coach pacing back and forth along the sidelines.
The diagram below shows several of coach's positions at various times. At each marked position, the coach makes a "U-turn" and moves in the opposite direction.
In other words, the coach moves from position A to B to C to D.
95 yds
Total Distance = _____
Total Displacement = _____
55 yds, left

15. In-Class assignment/homework
Finish Lecture Tutorial Questions