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

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 Step 2

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 Step 3

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 Step 3

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 Step 4

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 Step 3

Introduce the activity Teacher master I, Stop or Crash Points Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 3

View sample card Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 4

View sample card How many points would you receive if you drew that card? Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 4

Practice with constant speed Notebook sheet 15, Stop or Crash Activity Data Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 5

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 Step 5

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 Step 5

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 Step 6

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

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 Step 3

Analyze results for mass Notebook sheet 16, Stop or Crash Questions Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 8

Analyze results for mass As the mass ____________ , kinetic energy ____________ . Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 8

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 Step 8

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 Step 8

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 Step 8

Analyze results for speed What happens when you increase the speed? Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 9

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 Step 9

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 Step 10

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 Step 11

Review relationships Kinetic energy depends on v. Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 12

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 Step 12

Review relationships Kinetic energy depends on v. Which statement is true? Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 12

Review relationships Kinetic energy depends on m. Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 12

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 Step 12

Review relationships Kinetic energy depends on m. Which statement is true? Gravity and Kinetic Energy Course, 3.2: Stop or Crash Step 12

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 Step 13

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 Step 13

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 Step 14

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 Step 15

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 Step 17