1. Week 3 Day 2: Topics Particle Model General Motion Model
Constant Velocity Model
Representations of Motion
Motion Graphs
Motion Diagrams
Velocity graph to Position
Answer: C
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2. Announcements: Particle Model General Motion Model
Constant Velocity Model
Representations of Motion
Motion Graphs
Motion Diagrams
Velocity graph to Position
Answer: C
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3. Homework Hints: Particle Model General Motion Model
Constant Velocity Model
Representations of Motion
Motion Graphs
Motion Diagrams
Velocity graph to Position
Answer: C
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4. General Motion and Constant Velocity Motion
General Motion Model - Definitions
Position
Distance
Displacement
Average Speed
Average Velocity
Instantaneous Speed
Instantaneous Velocity
Constant v motion - Representations of motion
Motion Diagram
X vs. t graphs
Vx vs, t graphs
Describing motion in words
Data table
Particle Model
Answer: C

5. Can you move?
Fill in the tables for these motion events by indicating whether or not a motion event is possible.  If it is, give an example.  If not, explain why not.
Displacement
Final Position
Possible?
Example/Explanation
Not 0
Average Speed
Average Velocity
Possible?
Example/Explanation
Not 0
Answer: B
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6. There and Back
You and a friend decide to drive to Las Vegas, Nevada on Saturday over Labor Day weekend to go to a concert with some friends who live there. You figure you have to reach the vicinity of Las Vegas by 6 PM in order to meet your friends for dinner before the concert.
It's 574 miles from UNM to the Las Vegas strip. You'd like to stop for lunch and gas bout noon. What does your average velocity need to be?
It's almost all highway driving from here to Las Vegas. If you keep your speed approximately constant, what speed should your speedometer read while you are driving?
After you return to UNM, what is your displacement from the time you left to go to Las Vegas? What is the total distance traveled? What is your average speed and velocity?
Answer: B
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7. Making a Motion Diagram3

8. Examples of Motion Diagrams8

9. The Particle Model
A simplifying model in which we treat the object as if all its mass were concentrated at a single point. This model helps us concentrate on the overall motion of the object.
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10. Position and Time
The position of an object is located along a coordinate system.
At each time t, the object is at some particular position. We are free to choose the origin of time (i.e., when t = 0).
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11. Which Way? Which way is this object moving?
Is it speeding up or slowing down?
How can you tell?
Answer: B
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12. Motion Diagram Examples
Assume speed changes occur quickly compared to time scale => will appear instantaneous
Slow then Fast
Fast, stop, Slow
Turnaround
Answer: B
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13. A. B. C. D. Checking Understanding
Here is a motion diagram of a car moving along a straight stretch of road:
Which of the following velocity-versus-time graphs matches this motion diagram?
Answer: C A. B. C. D.
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14. Answer
Here is a motion diagram of a car moving along a straight stretch of road:
Which of the following velocity-versus-time graphs matches this motion diagram?
Answer: C C.
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15. Where’s the train?
A train is moving at a steady 30 m/s. At t = 0, the engine passes a signal light at x = 0. Without using any formulas, find the engine's position at t = 1s, 2s, and 3s.
Express your reasoning in words.
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16. Where’s the train?
A train is moving at a steady 30 m/s. At t = 0, the engine passes a signal light at x = 0. Without using any formulas, find the engine's position at t = 1s, 2s, and 3s.
Express your reasoning in words.
EQUATION FROM GRAPH
EQUATION FROM AREA
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17. Checking Understanding
A graph of velocity versus time for a hockey puck shot into a goal appears like so:
Which of the following position graphs matches the above velocity graph? A. B. C. D.
Answer: D
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18. Answer
A graph of velocity versus time for a hockey puck shot into a goal appears like so:
Which of the following position graphs matches the above velocity graph?
Answer: D A. B. C. D.
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19. Example Problem
A car moves along a straight stretch of road. The graph below shows the car’s position as a function of time.
At what point (or points) do the following conditions apply?
The displacement is zero.
The speed is zero.
The speed is increasing.
The speed is decreasing.
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20. Acceleration Acceleration is: The rate of change of velocity
The slope of a velocity- versus-time graph
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21. Particle Motion:
The picture above is made with a stroboscope (a light that flashes at regular time intervals) made at two frames of film per second, of a ball rolling along a track. The track has a 3.0-m-long sticky section.
Make a position-versus-time graph for the ball. Because you have data only at certain instants of time, your graph should consist of dots that are not connected together.
What is the change in the ball’s position from t = 0 s to t = 1.0 s?
c. What is the change in the ball’s position from t = 2.0 s to t = 4.0 s?
d. What is the ball’s velocity before reaching the sticky section?
e. What is the ball’s velocity after passing the sticky section?
f. Determine the ball’s acceleration on the sticky section of the track.
Answer: C
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22. Human Motion Demo - Trial 10
In each of the next four trials, you have to try to find a way to move such that you match the given representation and fill in the other two representations. (i.e. you are given a velocity vs. time graph and have to move to create the same velocity vs. time graph)
Description of motion from Trial #10
Answer: C
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