1. Lab 2-3-2: Stop or Crash?
December 5-6, 2017 – Pages 74-75

2. Focus question
How does the kinetic energy of an object change when its speed or mass changes?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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3. The Law of Conservation of Energy
Energy can neither be created nor destroyed. It can only be transferred or converted.
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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4. Introduce the activity
This activity is called Stop or Crash. Your group will get nine cards in a deck. Each card has a short scenario that may result in damage.
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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5. What is a Joule?
The joule (j) is a unit that can be used to measure kinetic energy. 1 Joule is the amount of energy it takes to apply 1 Newton of force over 1 meter 1j = 1N * 1m One kilojoule (kj) is equal to 1,000 j. One calorie on the bike or in food is about 4200 j
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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6. Introduce the activity
You will take turns drawing a card.
The person who drew the card will read it aloud to the others in the group.
That person will record their points in the box on the bottom of the notebook sheet.
Then every group member will record the kinetic energy of the vehicle on the notebook sheet.
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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7. Introduce the activity
Teacher master I, Stop or Crash Points
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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8. View sample card Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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9. View sample card
How many points would you receive if you drew that card?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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10. Practice with constant speed
Notebook sheet 15, Stop or Crash Activity Data
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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11. Practice with constant speed
In this analysis, what variable is being controlled (kept the same)?
What variable is being tested (changed)?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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12. Practice with constant speed
The unit of mass in this activity is the “sports car,” which represents the mass of one car. The activity has three distinct masses of vehicles. • Sports car • SUV = 3 sports cars • Semitrailer truck = 37 sports cars
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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13. Practice with constant mass
In this analysis, what variable is being controlled (kept the same)?
What variable is being tested (changed)?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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14. You Need to Write 1 3 37 11 22 44 3600 3600 44 m/s (Bottom)
Sports Car Mass (Top)
44 m/s (Bottom)
Mass in Sports Cars
Kinetic Energy (kj) 1
3600 3 37
Speed (m/s)
Kinetic Energy (kj) 11 22 44
3600

15. Introduce the activity
You will take turns drawing a card.
The person who drew the card will read it aloud to the others in the group.
That person will record their points in the box on the bottom of the notebook sheet.
Then every group member will record the kinetic energy of the vehicle on the notebook sheet.
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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16. Analyze results for mass
Notebook sheet 16, Stop or Crash Questions
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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17. Analyze results for mass
As the mass ____________ , kinetic energy ____________ .
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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18. Analyze results for mass
To answer the next question, look only at the top table at first. In this table, the speed is constant at 11 m/s. So we’ve controlled for speed and can look at the effect of mass on kinetic energy.
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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19. Analyze results for mass
Mathematically, how does kinetic energy depend on mass? HINT: If mass triples (from sports car to SUV), what happens to the kinetic energy?
If the mass increases 37 times (from sports car to semitrailer truck), what happens to the kinetic energy?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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20. Analyze results for mass
If the mass were to increase 12 times, what would happen to the kinetic energy?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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21. Analyze results for speed
What happens when you increase the speed?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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22. Analyze results for speed
As the speed ____________ , kinetic energy ____________ .
Mathematically, how does kinetic energy depend on speed? HINT: If speed doubles (from 11 m/s to 22 m/s), what happens to the kinetic energy?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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23. Confirm speed relationship
If speed quadruples (from 11 m/s to 44 m/s), what happens to the kinetic energy?
If the speed were to increase five times, what would happen to the kinetic energy?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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24. Apply to collisions Discuss this question in your group.
What do speed limits have to do with kinetic energy and safety in collisions?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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25. Review relationships Kinetic energy depends on v.
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26. Review relationships What does the symbol v represent?
Which statement shows the correct relationship between kinetic energy and speed?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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27. Review relationships Kinetic energy depends on v.
Which statement is true?
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28. Review relationships Kinetic energy depends on m.
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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29. Review relationships What does the symbol m represent?
Which statement shows the correct relationship between kinetic energy and mass?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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30. Review relationships Kinetic energy depends on m.
Which statement is true?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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31. Practice applying knowledge
If the speed of an airplane increases by a factor of 4, how much has its kinetic energy increased?
How does the kinetic energy of a person on a bike with combined mass of 40 kg compare to the kinetic energy of a person on a bike with combined mass of 80 kg, if they are both going 5 m/s?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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32. Practice applying knowledge
If an object’s speed is reduced by half and its mass increases by a factor of 2, does its kinetic energy increase or decrease? By how much?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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33. Review vocabulary
Spend a few minutes reviewing the vocabulary for this part. Update the vocabulary index and table of contents in your notebook.
joule
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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34. Answer the focus question
How does the kinetic energy of an object change when its speed or mass changes?
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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35. Review notebook entries
Share your focus question responses with a partner. Ask questions, give each other constructive feedback, and revise your entries if needed. Discuss how the concept of proportion helps you to think about energy as mass or speed changes.
Gravity and Kinetic Energy Course, 3.2: Stop or Crash
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