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Unit 1: Phenomenon – The Physics of Skydiving Lesson 2.c Kinematics –Introductory Analysis of Motion California Standard Addressed PH1. Newton’s laws predict the motion of most objects. As a basis for understanding this concept: Student Performance Outcomes Students will categorize the type of motion experienced by an object (uniform velocity or uniform acceleration) based on ticker tape patterns and graphical patterns of position vs. time data. Students will match the motion defined by position vs. time graphs using a motion detector and computer interface.

DO NOT WRITE ON THIS HANDOUT

Engage

Examine the picture on the left. 1. What would happen to the distance between the cones if the driver speeds up? 2. What would happen to the distance between the cones if the driver slowed down?

3. Based on the patterns shown below, predict if the truck speeding up, slowing down, going at a slow steady speed, going at a fast steady speed. One cone is dropped every second. The direction of motion is to the right.

a)

b)

c)

d)

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4. Graph the data for each of the cone patterns shown above. Remember, each cone represents 1 second.

a) b)

c) c) 5. If the cones are separated by a small distance, is the truck moving at a slow speed or a fast speed? How do you know? 6. If the cones are separated by a large distance, is the truck moving at a slow speed or a fast speed? How do you know? 7. If a graph of position vs. time shows a straight line, is the truck moving at a steady speed, or is the speed of the truck changing (speeding up or slowing down)? How do you know? 8. If a graph of position vs. time shows a curved line, is the truck moving at a steady speed, or is the of the truck changing (speeding up or slowing down)? How do you know? The ticker tape machine produces information very much like the cones coming off of the truck. You task is to now relate the type of motion to the pattern of dots on the tape. The ticker tape machine taps out dots on the paper tape at a regular rate (about 60 per second).

Machine turned on. Tape pulled, dots printed on tape

Explore

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◊ The teacher will provide you with 4 tapes and a ticker tape timer (can you say that really fast 10 times?) He will demonstrate how to use the machine.

The motion you are asked to produce

Your prediction (How do you think the dots will appear on the tape? – draw dots in the space below)

Your observation (How did the dots actually appear on the tape? –draw dots in the space below)

Tape pulled at a slow steady speed

Tape pulled at a fast steady speed

Tape pulled with an increasing speed (slow to fast)

Tape pulled with a decreasing speed (fast to slow)

Tape pulled with an increasing then decreasing speed (slow to fast then slow)

9. Redraw the table below in your notebook and arrange the descriptions, the ticker tape patterns, and the graphs so they match correctly.

Description

Dot Pattern

Graph

1. The tape is slowing down. I

A

2. The tape is speeding up. II

B

3. The tape is moving at a steady fast speed.

III . . . . . . .

C

4. The tape is moving at a steady slow speed.

IV

D

5. The tape is speeding up, then slowing down.

V

E

I. Motion deals with the changes of an object’s position over time.

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10. Which of the graphs shown below represents an object that is not moving? Support your answer.

A) B) C) D) E)

© Tom Barnett. All Rights Reserved. Used with Permission.

11. This is an image of a single pair of scissors that are falling. How do you know the scissors are falling? Be specific in your explanation. 12. Which of the following graphs do you think best matches the position of the scissors over time? Support your thinking.

A) B) C) D) E)

13. Which of the following graphs do you think best matches the speed of the scissors over time. Support your thinking. We are using the term speed here to indicate how fast the scissors are falling.

A) B) C) Student A says, “I think that the scissors are moving at a steady speed. This means that the graph in number 13 could be either C or D. If the scissors are moving at a steady speed, then a graph of speed vs. time should look like B in number 14. I think that it should be B because the speed isn’t changing on the graph.” Student B says, “I think that the scissors are speeding up as they fall because the distances are getting bigger. This means that the graph in number 13 should be B. Since the scissors are speeding up, I think that number 14 should be C since the speed is getting higher as time passes.” 14. Which student do you agree with? Support your answer.

15. Look at the graph on the left. Identify the type of motion the object is experiencing in each segment. I. II. III. IV.

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16. Look at the graph on the left. Identify the type of motion the object is experiencing in each segment. Support your ideas. I. II. III.

17. Sketch the appearance of a position vs. time graph that would match the speed – time graph from question 16.

Explain 18. List evidence that could be used to prove that an object was moving with a steady speed versus an increasing speed.

Use these graphs for 19-23

a) b) c) d) e) 19. Which of these graphs represents an object that is speeding up? 20. Which of these graphs represents and object that is slowing down? 21. Which of these graphs represents and object that is stationary? 22. Which of these graphs represents an object that is moving at a slow steady speed? 23. Which of these graphs represents and object that is moving with a fast steady speed?

Use these graphs for 24-25

a) b) c) 24. Which of these graphs represents an object that is speeding up? 25. Which of these graphs represents and object that is moving with a steady speed? 26. This lesson has added another “language” (ticker tape timer patterns) to our repertoire of ways to describe different motions. We can also describe it using words or graphs. What are the strengths and weaknesses of each “language”?