Science IPC Unit 09 Exemplar Lesson 01: Potential and Kinetic Energy

Transcription

1 Science Unit 09 Exemplar Lesson 01: Potential and Kinetic Energy Integrated Physics and Chemistry Science Unit: 09 Lesson: 01 Suggested Duration: 10 days This lesson is one approach to teaching the State Standards associated with this unit. Districts are encouraged to customize this lesson by supplementing with district-approved resources, materials, and activities to best meet the needs of learners. The duration for this lesson is only a recommendation, and districts may modify the time frame to meet students needs. To better understand how your district may be implementing CSCOPE lessons, please contact your child s teacher. (For your convenience, please find linked the TEA Commissioner s List of State Board of Education Approved Instructional Resources and Midcycle State Adopted Instructional Materials.) Lesson Synopsis Students will develop an understanding of the types of mechanical energy and how they are conserved. This will be done by engaging in explorative activities that involve the motion of objects and how energy is conserved while the object s motions are changed. The emphasis will be on how objects in motion have kinetic energy. There are many types of stored energy, and that energy is conserved in a closed system. There will be opportunities to tie in, relate, and practice techniques for finding quantitative values that will enforce the conceptual ideas presented. TEKS The Texas Essential Knowledge and Skills (TEKS) listed below are the standards adopted by the State Board of Education, which are required by Texas law. Any standard that has a strike-through (e.g. sample phrase) indicates that portion of the standard is taught in a previous or subsequent unit. The TEKS are available on the Texas Education Agency website at Scientific Process TEKS I.5 Science concepts. The student recognizes multiple forms of energy and knows the impact of energy transfer and energy conservation in everyday life. The student is expected to: I.5A Recognize and demonstrate that objects and substances in motion have kinetic energy such as vibration of atoms, water flowing down a stream moving pebbles, and bowling balls knocking down pins. I.5B Demonstrate common forms of potential energy, including gravitational, elastic, and chemical, such as a ball on an inclined plane, springs, and batteries. I.5D Investigate the law of conservation of energy. I.2 Scientific processes. The student uses scientific methods during laboratory and field investigations. The student is expected to: I.2E Communicate valid conclusions. GETTING READY FOR INSTRUCTION Performance Indicators High School Science Integrated Physics and Chemistry Unit 09 PI 01 Given a specific example, create a chart that shows energy s journey from potential to kinetic. In a written summary, explain the chart, and describe how the energy was ultimately conserved. Standard(s): I.2E, I.5A, I.5B, I.5D ELPS ELPS.c.1C, ELPS.c.2E, ELPS.c.3D, ELPS.c.4D, ELPS.c.5B Key Understandings Objects and substances in motion have kinetic energy. What factors affect the kinetic energy of a substance or an object? How does an object acquire Kinetic Energy? Potential energy comes in different forms. What factors affect an objects gravitational potential energy? What are other forms of stored or potential energy? Energy is conserved in a closed system. How are the energies involved in a falling object transformed? How is the total mechanical energy of a system affected by the potential energy and the kinetic energy of the system? Vocabulary of Instruction law of conservation of energy chemical energy energy transformation mechanical energy elastic potential Last Updated 05/29/2013 page 1 of 33

2 kinetic energy potential energy gravitational potential energy energy Integrated Physics and Chemistry Science Unit: 09 Lesson: 01 Suggested Duration: 10 days Materials baseball (1 at Station 2) batteries (2 D-cell per Station 1) battery (9 volt, 1 for demonstration) clamp (1 per group) duct tape egg (raw, 1 per group, keep extras in case of breakage in handling) (per group) egg sack (nylon mesh, see Advance Preparation, 1 per group) electronic balance (1 per group) flat surface (for Station 2) golf ball (1 at Station 2) marble (1 per group) markers (per group) masking tape (1 roll per group) metal tongs (1 per Station 1) meter stick (1 per group) nickel (1 at Station 3) paperclips (non-coated, 2 per group at Station 1) poster board (or other paper for charts, per group) ring stand (1 per group) roller coaster track (per group) rubber bands (long, several per group) steel wool (at Station 1) stopwatch (1 per group) tennis balls (3 at Station 4) tennis balls (must be identical, 2 per Station 2) toy popper (1 for demonstration) wire (1 per group) Attachments All attachments associated with this lesson are referenced in the body of the lesson. Due to considerations for grading or student assessment, attachments that are connected with Performance Indicators or serve as answer keys are available in the district site and are not accessible on the public website. Teacher Resource: Energy Conversions Engagement Activities (see Advance Preparation) Handout: Rubber Band Egg Drop (1 per student) Handout: Rubber Band Egg Drop Analysis Sheet (1 per student) Teacher Resource: Rubber Band Egg Drop Analysis Sheet KEY Handout: Guided Notes for PowerPoint: Energy (1 per student) Teacher Resource: PowerPoint: Energy Handout: Energy Practice (1 per student) Teacher Resource: Energy Practice KEY Handout: Kinetic Energy and Potential Energy Problems (1 per student) Teacher Resource: Kinetic Energy and Potential Energy Problems KEY Handout: Roller Coaster Lab (1 per student) Teacher Resource: Roller Coaster Lab KEY Teacher Resource: Performance Indicator Instructions KEY (1 for projection) Resources None Identified Advance Preparation 1. Prior to Day 1: Last Updated 05/29/2013 page 2 of 33

3 Use the Teacher Resource: Energy Conversions Engagement Activities to create two sets of materials for each station. Using two sets of stations will allow students to move through the activities in one class period. Place the materials in a shoe box or tub for each station, so students can have all materials readily available when they begin. For durability, make one copy of the Teacher Resource: Energy Conversions Engagement Activities on cardstock and laminate. Each page contains the procedures for one station. If you are going to set up two sets of stations, you will need two copies of the procedures. 2. Prior to Day 2, cut the nylon mesh into squares for the egg sacks (1 per group). 3. Prepare attachment(s) as necessary. Background Information This unit bundles student expectations that relate to potential and kinetic energy. Integrated Physics and Chemistry Science Unit: 09 Lesson: 01 Suggested Duration: 10 days During this unit, students learn to recognize and demonstrate common forms of kinetic and potential energy. Students also investigate the law of conservation of energy. In the following unit, students will continue the focus on energy through a study of waves. Energy cannot be created or destroyed, only transferred or transformed. This is known as the law of conservation of energy and is essential to understanding motion and energy. Stored energy comes in many forms- stored energy in chemical bonds, energy due to an objects position, elastic potential energy, energy of motion, heat, etc. For students to gain an understanding of energy, it is important for there to be active experiences, so that students can tie their own life experiences to conceptual ideas and formal terminology. INSTRUCTIONAL PROCEDURES Instructional Procedures ENGAGE Energy Conversions 1. Conduct a brief discussion to ascertain student ideas regarding energy conversions. This content has been addressed in middle school, so should be familiar to students. It may be helpful to use an illustration such as turning on a light fixture and asking students to point out the various conversions occurring. 2. Divide the class into groups of Inform students they will be participating in several station activities (see Advance Preparation) to explore energy conversions. Ask students to bring their science notebooks with them in order to answer questions and record data. 4. Allow students 8 10 minutes at each station. Give a warning signal to let students know that it is time to clean up materials. Give a second signal to let students know that it is time to rotate stations. 5. When the students have completed all of the stations, facilitate a discussion in which students reflect on relevant terms (See step 11 below.). 6. Write the terms on the board, ask groups to use prior knowledge, and discuss possible operational definitions for each term. 7. Ask a few groups to share their definitions out loud for the term kinetic energy. 8. Work with students to revise their definitions to come up with a version of the formal definition for kinetic energy (shown below), and ask the question that follows. Ask students to justify their answers. 9. Instruct students to record the formal definitions in science notebooks. 10. Continue steps 6 through 9 for each additional term. Kinetic Energy - Energy that a moving object has due to its motion. Which of the stations had examples of kinetic energy? (Station 2 Kinetic Energy and Station 3 Slingshot) Elastic Potential Energy - Energy stored by something that can be stretched or compressed. Which of the stations demonstrated elastic potential energy? (Station 3 Slingshot) Chemical Potential Energy - Energy stored in chemical bonds. Which of the stations demonstrated chemical potential energy? (Station 1 with the battery) Some students may realize that it takes chemical energy for them to roll the balls or stretch the rubber band as well. Gravitational Potential Energy - Energy stored due to an objects position above Earth s surface. Which station demonstrated gravitational potential energy? (Station 4 with the tennis balls at different heights) Notes for Teacher NOTE: 1 Day = 50 minutes Suggested Day 1 Materials: batteries (2 D-cell per Station 1) duct tape (1 roll per Station 1) metal tongs (1 per Station 1) paperclips (non-coated, 2 per group at Station 1) steel wool (at Station 1) baseball (1 at Station 2) golf ball (1 at Station 2) tennis balls (must be identical, 2 per Station 2) flat surface (for Station 2) rubber band (1 or more at Station 3) nickel (1 at Station 3) meter stick (1 at Station 3) duct tape (1 roll at Station 4) tennis balls (3 at Station 4) Attachments: Teacher Resource: Energy Conversions Engagement Activities (see Advance Preparation) Safety Notes: Wear safety goggles. Steel wool heats up, so caution students to keep the circuit connected only for a short period of time. Instructional Notes: You may decide to have 2 3 students per group and two sets of each station, rather than larger groups with one station. This will allow all students to move through activities within the class period. Misconceptions: Last Updated 05/29/2013 page 3 of 33

4 Integrated Physics and Chemistry Science Unit: 09 Lesson: 01 Suggested Duration: 10 days Students may think an object at rest has no energy. Students may think the only type of potential energy is gravitational. Students may think energy is confined to some particular origin, such as energy from food or energy from the electricity company. Science Notebooks: Students answer questions and record data during station activities. EXPLORE Rubber Band Egg Drop Suggested Days 2 and 3 1. On Day 2, students will conduct steps 1 6 from the Handout: Rubber Band Egg Drop. You may wish to use the same groups from the previous day s activities. 2. Explain to students they will be conducting an investigation called the Rubber Band Egg Drop. They will be conducting steps 1 6 from the Handout: Rubber Band Egg Drop today (Day 2). They will be working in same groups from the previous day s activities. 3. Inform students that portions of their grade will come from work they do together and another portion will come from the analysis that will be done after the investigation on Day Distribute the Handouts: Rubber Band Egg Drop and Rubber Band Egg Drop Analysis Sheet to each student. Ask students to read the instructions, and answer any questions they may have regarding the directions. 5. Caution students on the appropriate use of the rubber bands. 6. Monitor student groups, and assist as necessary as students complete the investigation. 7. On Day 2, explain to students that they will be testing their egg drop predictions based on steps 7 8 of the procedure. 8. Inform students that they will need to set up their stations and be ready to demonstrate the egg drop, according to the lab procedure. 9. Monitor student groups as they set up their stations. 10. Note: In order to save instructional time, while the instructor is observing and monitoring each group s drop, the other students will be working on the Handout: Rubber Band Egg Drop Analysis Sheet. (per group) Materials: egg (raw, 1 per group, keep extras in case of breakage in handling) egg sack (nylon mesh, see Advance Preparation, 1 per group) wire (1 per group) rubber bands (long, several per group) meter stick (1 per group) ring stand (1 per group) clamp (1 per group) masking tape (1 roll per group) Attachments: Handout: Rubber Band Egg Drop (1 per student) Handout: Rubber Band Egg Drop Analysis Sheet (1 per student) Teacher Resource: Rubber Band Egg Drop Analysis Sheet KEY Instructional Note: For best results and for all students to have opportunity to learn and take part, it is suggested to divide the class into groups of three per station. EXPLAIN Guided Discussion Suggested Day 4 1. Distribute a copy of the Handout: Guided Notes for PowerPoint: Energy to each student. 2. Instruct students to use the handout as they view the Teacher Resource: PowerPoint: Energy. 3. Show the PowerPoint, and facilitate a discussion of each slide. Require students to use details from the Engage and Explore activities as evidence of concepts. 4. Pause when you reach slide #9. 5. Conduct the process specified in the slide (using the steel wool), and allow students to make observations. Instruct student to add information to their notes appropriately. 6. When the discussion reaches slide #10, pause again, and demonstrate the toy popper multiple times. 7. Allow students to fill in their notes appropriately. 8. At the end of the PowerPoint discussion, project the following questions and ask students to respond in their science notebooks. Ask: What factors affect the kinetic energy of a substance or object? (The mass and velocity) Materials: steel wool (for demonstration) battery (9 volt, 1 for demonstration) metal tongs (1 for demonstration) toy popper (1 for demonstration) Attachments: Handout: Guided Notes for PowerPoint: Energy (1 per student) Teacher Resource: PowerPoint: Energy Instructional Note: Review information and observations from the Engage and Explore activities to clarify what has been learned about types of energy up to this point in the lesson. Misconceptions: Last Updated 05/29/2013 page 4 of 33

5 How does an object acquire kinetic energy? (By converting some kind of potential energy to motion) What factors affect an objects gravitational potential energy? (The mass and height of the object) What are other forms of stored or potential energy? (Chemical and elastic potential energy) Integrated Physics and Chemistry Science Unit: 09 Lesson: 01 Suggested Duration: 10 days Students my think energy is lost in many energy transformations. Students may wonder if energy is conserved, why we are running out of it. 9. If time allows, ask students to share their responses in groups or with the class. EXPLAIN Energy Practice Problems Suggested Day 5 1. Distribute a copy of the Handout: Energy Practice to each student. 2. Instruct students to work with a partner to complete the handout. They will have approximately half of the class period to complete it. 3. Students may use the previous day s notes to review and reinforce appropriate use of formulas. 4. For the second half of the class period, instruct partner groups to work with another partner group to discuss each question. Student partners will take turns explaining how they solved each problem and discussing any discrepancies. Attachments: Handout: Energy Practice (1 per student) Teacher Resource: Energy Practice KEY Science Notebooks: Students use the previous day s notes to review and reinforce appropriate use of formulas. 5. Monitor each group to assist and answer any questions. 6. Allow a few minutes at the end of class to review the handout and clarify any misconceptions, based upon your observations from student groups questions. Allow students to revise their work as needed. EXPLAIN KE and PE Problems Suggested Day 6 1. Each student will complete the Handout: Kinetic Energy and Potential Energy Problems. Students should show all work and include all appropriate units with their answers. 2. Monitor and assist students as they complete the handouts. 3. At the end of class, clarify any misconceptions based upon your observations of student s work during the class. Allow students to revise their work as needed. Attachments: Handout: Kinetic Energy and Potential Energy Problems (1 per student) Teacher Resource: Kinetic Energy and Potential Energy Problems KEY ELABORATE Roller Coaster Design Suggested Days 7 and 8 1. Divide the class into groups of four. Distribute a copy of the Handout: Roller Coaster Lab to each student. 2. Instruct students to read the handout, and answer any questions students may have regarding the instructions. 3. Inform students they will have two days to build their roller coasters, gather data, and answer the analysis questions. 4. Monitor students as they construct their roller coasters. Assist students with time management in order for the class to have time to gather data and complete their analyses. 5. Allow time at the end of Day 2 to ask the following questions and discuss student responses. Ask: How are the energies involved in a falling object transformed? (GPE becomes KE as the coaster falls and speeds up.) How is the total mechanical energy of a system affected by the potential energy and kinetic energy of the system? (Total mechanical energy stays the same.) Materials: roller coaster track (per group) masking tape (1 roll per group) marble (1 per group) stopwatch (1 per group) meter stick (1 per group) electronic balance (1 per group) Attachments: Handout: Roller Coaster Lab (1 per student) Teacher Resource: Roller Coaster Lab KEY Instructional Notes: During this investigation, allow students to have some creative freedom. Be present as an advisor, but allow students to deal with the trials and errors of design creation. If need be, some of the analysis can be completed at home. EVALUATE Performance Indicator Suggested Days 9 and 10 High School Science Integrated Physics and Chemistry Unit 09 PI 01 Given a specific example, create a chart that shows energy s journey from potential to kinetic. In a written summary, explain the chart, and describe how the energy was ultimately conserved. Standard(s): I.2E, I.5A, I.5B, I.5D ELPS ELPS.c.1C, ELPS.c.2E, ELPS.c.3D, ELPS.c.4D, ELPS.c.5B Materials: poster board (or other paper for charts, per group) markers (per group) Last Updated 05/29/2013 page 5 of 33

6 1. Refer to the Teacher Resource: Performance Indicator Instructions KEY for information on administering the performance assessment. Instructional Note: You may want to review KE and PE formulas again or instruct students to use their notes to help complete the charts and summaries. Integrated Physics and Chemistry Science Unit: 09 Lesson: 01 Suggested Duration: 10 days Science Notebooks: Students use their notes to review and reinforce appropriate use of formulas. Last Updated 05/29/2013 page 6 of 33

7 Energy Conversions Engagement Activities STATION 1: Chemical Potential Energy One of the most useful inventions of the 19 th Century was the electric light bulb. Being able to light up the dark has enabled people to work and play longer. A light bulb converts electric energy into heat energy and light, another form of energy. The following activity shows electrical energy being changed into other forms of energy. Materials: D-cell batteries (2) duct tape metal tongs non-coated paper clips (2) steel wool Safety Notes: Steel wool can become hot. Keep the circuit connected only for a short period of time. Procedure: 1. Obtain two D-cell batteries, duct tape, metal tongs, two non-coated paper clips, and some steel wool. Separate the steel wool into thin strands, and straighten the paper clips. 2. Tape the batteries together with a (+) terminal of one battery connected to the (-) terminal of the other battery. Tape one end of one paper clip to the (+) terminal and the other paper clip to the (-) terminal. Do not allow the open ends of the paper clip to touch. 3. While holding the steel wool with the tongs, briefly complete the circuit by placing the steel wool in contact with both of the paper clip ends. 4. In your science notebooks, describe what happened to the steel wool. 5. What changes did you observe? Why do you think these changes occurred? Where does the energy in the battery come from? Use complete sentences. 6. Clean up station materials for the next group. 2012, TESCCC 12/06/12 page 1 of 4

8 Energy Conversions Engagement Activities Materials: baseball (or other heavy ball)(1) golf ball (or other light ball)(1) tennis balls (must be identical balls)(2) flat surface STATION 2: Kinetic Energy Procedure: 1. Roll the baseball and golf ball across the flat surface at the same speed. 2. In your science notebooks, describe the kinetic energy of each ball. Use complete sentences. 3. Take the two tennis balls, and roll them across the flat surface with the same speed. In your science notebook, describe the kinetic energy of each ball. Use complete sentences. 4. Take the two tennis balls, and roll them so that one ball is rolling faster than the other. In your science notebook, describe which ball has the greater kinetic energy. Use complete sentences. 5. Clean up station materials for the next group. 2012, TESCCC 12/06/12 page 2 of 4

9 Energy Conversions Engagement Activities STATION 3: Slingshot Elastic Potential Energy Materials: rubber band nickel meter stick Safety Notes: Exercise caution with the rubber bands. Procedure: 1. Using two fingers, carefully stretch a rubber band on a table until there is no slack. 2. Place a nickel on the table, slightly touching the mid-point of the rubber band. 3. Push the nickel back 0.5 cm into the rubber band and release. Measure the distance that the nickel travels. Record the data in your science notebooks. 4. Repeat the steps three more times, pushing the nickel back an additional 0.5 cm each time. 5. How did the takeoff speed of the nickel seem to change, relative to the distance that you stretched the rubber band? Use complete sentences to record your responses in your science notebooks. 6. What can you infer about the kinetic energy of the nickel? Use complete sentences to record your responses in your science notebooks. 7. Clean up station materials for the next group. 2012, TESCCC 12/06/12 page 3 of 4

10 Energy Conversions Engagement Activities STATION 4: Gravitational Potential Energy Materials: duct tape tennis balls (3) Procedure: 1. Use duct tape to attach one tennis ball to the wall above the front white or chalk board. 2. Place the second tennis ball in the tray of the front board. 3. Place the third tennis ball on the floor below the front board. 4. How do the gravitational potential energies of the three balls compare? Record your answers using complete sentences in your science notebooks. 5. Clean up station materials for the next group. 2012, TESCCC 12/06/12 page 4 of 4

11 Rubber Band Egg Drop (Adapted from Egg Bungee Jump, by Thomas Tretter: Background: You will be gathering data on a rubber band raw egg drop using rubber bands as a type of bungee cord. The goal of this investigation is to have the egg drop from two meters and to get as close as possible to the floor without hitting it. It will be your task to determine how many rubber bands should be used to create the bungee cord. After a successful drop, concepts of energy, force, and motion will be applied to the egg drop. Materials: egg (1) egg sack (nylon, mesh square)(1) wire (1) rubber bands meter stick (1) ring stand (1) clamp (pendulum holder on diagram)(1) masking tape Procedure: 1. Put a raw egg in the nylon, mesh square, and fold it up into a bag, wrapping the top tightly with wire. Make a loop at the top of the wire- the rubber bands will be attached to this loop. Make the length of the wire significantly shorter (approximately half works well) than the length of the rubber band. When lifted, the bottom of the egg should be even with the clamp for the first drop. (See Figure 1 below.) FIGURE 1 FIGURE 2 2. Put a ring stand with a clamp attached at the edge of a lab table with the clamp facing outward. 3. Use masking tape to secure a meter stick near the ring stand so that the zero mark is in line with the clamp. One person will need to hold down the ring stand so that it will be stable during the egg drop (See Figure 2 above.). 4. Put one rubber band on the wire loop- thread it through itself as an easy way to attach it to the loop. Place the free end of the rubber band on the clamp. 2012, TESCCC 05/29/13 page 1 of 3

12 5. Conduct one practice/trial run by putting a finger over the top of the clamp (so that the rubber band does not jump off) and dropping the egg package from the height of the clamp (See Figure 3 below.). FIGURE 3 6. Observe approximately how far the egg falls. Conduct your actual trials (three drops), and record how far the egg falls from the clamp in the table below. NOTE: A teammate should catch the egg after it starts back up so that the egg doesn t hit the lab table or ring stand and crack after its bounce! 7. Loop a second rubber band through the first one, and repeat the drop and measure. Continue recording the fall distance for three and four rubber bands. You may not use more than four rubber bands for this portion of the data collection. 8. Make a graph of distance fallen (y-axis) versus the number of rubber bands (x-axis). Distance Fallen (cm) Number of Rubber Bands Trial 1 Trial 2 Trial 3 Average , TESCCC 05/29/13 page 2 of 3

13 9. From the graph, predict the number of rubber bands to use for a 2-meter drop. Remember, YOUR GOAL is to get as close as possible to the floor without the egg hitting it for the 2-meter drop. Record your prediction here: rubber bands. 10. Set up your egg drop according to your above prediction. Adjust the clamp so that the starting point is two meters from the floor. Position your meter stick so that the zero mark is on the floor. You will get three trials to demonstrate your drop. You may make adjustments after each trial, but you may not practice after the adjustment. 11. Investigation Grade: The above portion of this investigation will earn points based on how well your egg performs. a. You must show your data table and graph properly recorded. b. Your grade will be 20 points minus the number of centimeters from the floor on the drop. Your teacher must be present to witness! Trial #1 Trial #2 Trial #3 c. If the egg hits on all trials and your data gathering technique is correct, you will receive a score of 10 points. All images courtesy of A. Kavich 2012, TESCCC 05/29/13 page 3 of 3

14 Rubber Band Egg Drop Analysis Sheet Energy Transformations Throughout the Drop time to reach 0 Energy of egg can be described as: (Losing/Gaining) GPE time to reach x (Losing/Gaining) KE Describe GPE: Describe KE: Describe Elastic PE: time to reach y Describe GPE: Describe KE: Describe Elastic PE: time to reach z 100% (KE/Elastic PE) 2012, TESCCC 12/06/12 page 1 of 1

15 Rubber Band Egg Drop Analysis Sheet KEY Energy Transformations Throughout the Drop time to reach 0 Energy of egg can be described as: 100% GPE (Losing/Gaining) GPE time to reach x (Losing/Gaining) KE Describe GPE: _Decreasing Describe KE: Increasing Describe Elastic PE: _None time to reach y Describe GPE: Decreasing Describe KE: Decreasing Describe Elastic PE: Increasing time to reach z 100% (KE/Elastic PE) 2012, TESCCC 12/06/12 page 1 of 1

16 Guided Notes for PowerPoint: Energy Section 1: The Nature of Energy Learning Goals: Distinguish between kinetic and potential energy. Calculate kinetic energy. Describe different forms of potential energy. Calculate gravitational potential energy. What is Energy? the ability to Kinetic Energy Kinetic Energy Equation kinetic energy (joules) = ½ mass (kg) [speed (m/s)] 2 Potential Energy 2012, TESCCC 12/06/12 page 1 of 4

17 Gravitational Potential Energy Gravitational Potential Energy Equation GPE (J) = mass (kg) acceleration due to gravity (m/s 2 ) height (m) Remember Acceleration due to gravity is Elastic Potential Energy Chemical Potential Energy 2012, TESCCC 12/06/12 page 2 of 4

18 Section 2: Conservation of Energy Learning Goals: Describe how energy can be transformed from one form to another. Explain how the mechanical energy of a system is the sum of the kinetic and potential energy. Discuss the law of conservation of energy. Energy Transformation Examples: Conversions between Kinetic and Potential Energy: 2012, TESCCC 12/06/12 page 3 of 4

19 Roller Coaster Example 1. Energy required for a ride comes from work done by the conveyor that lifts the cars and passengers. 2. Energy from the initial work is stored as GPE at the top of the first hill. 3. Energy transformations begin: kinetic to potential to kinetic, etc., heat energy, and sound energy. The Law Of Conservation Of Energy 2012, TESCCC 12/06/12 page 4 of 4

20 Energy Practice 1. An object has kinetic energy. What other details do you need to know to find the amount of kinetic energy the object possesses? I need to know its. (a) A car with a mass of 1500 kg is traveling at a speed of 8 m/s. What is the car s kinetic energy? Answer: (b) If the mass of the car doubles, what happens to the kinetic energy? Answer: (c) If the car s speed doubles, what happens to the kinetic energy? Answer: (d) If the car s speed triples, what happens to the kinetic energy? Answer: 2012, TESCCC 12/06/12 page 1 of 2

21 2. The diagram below shows a toy popper that has been stretched and placed on the floor. It is ready to launch. Once it launches, position C is the highest point the popper reaches before it begins descending back to the floor. C (a) What type of energy does the popper have at its starting position? (b) What type of energy does the popper have at the halfway up point? (c) At what position(s) does the popper have 0 KE? (d) At what position(s) does the popper have 0 GPE? (e) At what position(s) does the popper have the greatest GPE? Images courtesy of A. Kavich 2012, TESCCC 12/06/12 page 2 of 2

22 Energy Practice KEY 1. An object has kinetic energy. What other details do you need to know to find the amount of kinetic energy the object possesses? I need to know its mass and velocity. (a) A car with a mass of 1500 kg is traveling at a speed of 8 m/s. What is the car s kinetic energy? KE = 1/2 mass x velocity 2 = (.5)(1500kg)(8m/s) 2 Answer: 48,000 J (b) If the mass of the car doubles, what happens to the kinetic energy? Answer: The kinetic energy of the car will double also. (c) If the car s speed doubles, what happens to the kinetic energy? Answer: It will increase by a factor of 4x. (d) If the car s speed triples, what happens to the kinetic energy? Answer: It will increase by a factor of 9x. 2012, TESCCC 05/29/13 page 1 of 2

23 2. The diagram below shows a toy popper that has been stretched and placed on the floor. It is ready to launch. Once it launches, position C is the highest point the popper reaches before it begins descending back to the floor. C (a) What type of energy does the popper have at its starting position? Elastic potential energy (b) What type of energy does the popper have at the halfway up point? Kinetic and gravitational potential (c) At what position(s) does the popper have 0 KE? At point C- its highest point (d) At what position(s) does the popper have 0 GPE? At the lowest point when it is on the ground (e) At what position(s) does the popper have the greatest GPE? At point C- its highest point Images courtesy of A. Kavich 2012, TESCCC 05/29/13 page 2 of 2

24 Kinetic Energy and Potential Energy Problems Solve the following problems on separate paper. Show your work. Kinetic Energy 1. Calculate the kinetic energy of a 3000 kg truck moving at the following speeds (answer in joules): a. 58 m/s b. 36 m/s c. 84 km/h (Hint: Convert to m/s before calculating the joules.) 2. A 25 kg child is using a 1kg skateboard to travel down a hill. If the child has 165 J of kinetic energy after traveling down the hill, what is the child's speed in meters per second? 3. A toy car is moving on a track at 4.0 m/s. If the toy car has 16 J of kinetic energy, what is the mass of the car in kilograms? Gravitational Potential Energy 1. Calculate the gravitational potential energy in the following systems: a. A 70 kg cliff diver 20 m above the ocean b. A 1350 kg car that is parked 45 m above the ground c. A 1000 kg rocket that has an altitude of 625 m 2. The Great American Dirt Corporation flies dirt around the United States. What is the gravitational potential energy of 10 containers of dirt that have a combined mass of 2600 kg, if the dirt is on a plane with an altitude of 1.5 km? (Hint: Convert the mass to kilograms and the height to meters before solving.) 3. A 5500 g bag is thrown out of a window. If the bag has J of gravitational energy at its highest point, how far above the ground was it in meters at its highest point? (Hint: Convert the mass to kilograms before solving.) 4. A skydiver has 360,000 J of gravitational potential energy as soon as they jumped out of the plane. If the skydiver jumped out of the plane at.6 km above the ground, what is the skydiver's mass in kilograms? (Hint: Convert the height to meters before solving.) 2012, TESCCC 05/29/13 page 1 of 1

25 Kinetic Energy and Potential Energy Problems KEY Kinetic Energy 1. Calculate the kinetic energy of a 3000 kg truck moving at the following speeds (answer in joules): a. 58 m/s KNOWN m = 3000 kg v = 58 m/s UNKOWN KE = J SUBSTITUTION: KE = 3000kg (58 m/s) 2 b. 36 m/s KNOWN m = 3000 kg v = 36 m/s 2 Answer: 5,046,000 J UNKNOWN KE = J SUBSTITUTION: KE = 3000kg (36 m/s) 2 2 Answer: 1,944,000 J FORMULA KE = mv 2 2 FORMULA KE = mv 2 c. 84 km/h (Hint: Convert to m/s before calculating the joules.) KNOWN UNKNOWN m = 3000 kg KE = J v = 84 km/h = m/s SUBSTITUTION: KE = 3000 kg (23.33 m/s) 2 2 FORMULA KE = mv 2 2 Answer: 816, J 2 2. A 25 kg child is using a 1kg skateboard to travel down a hill. If the child has 165 J of kinetic energy after traveling down the hill, what is the child's speed in meters per second? KNOWN KE = 165 J m = 26 kg UNKNOWN V = m/s SUBSTITUTION: V = 2(165 J) 26 kg Answer: 3.56 m/s FORMULA V = 2KE m 3. A toy car is moving on a track at 4.0 m/s. If the toy car has 16 J of kinetic energy, what is the mass of car in kilograms? KNOWN KE = 16 J V = 4.0 m/s UNKNOWN m = kg SUBSTITUTION: M = _2 (16 J)_ = 32 J_ (4.0 m/s) 2 16 m 2 /s 2 Answer: 2 kg FORMULA M = 2KE V , TESCCC 05/29/13 page 1 of 3

26 Gravitational Potential Energy 1. Calculate the gravitational potential energy in the following systems: a. A 70 kg cliff diver 20 m above the ocean KNOWN m = 70 kg h = 20 m g = 9.8 m/s 2 UNKNOWN GPE = J SUBSTITUTION: GPE = 70 kg 9.8 m/s 2 20 m Answer: 13,720 J b. A 1350 kg car that is parked 45 m above the ground KNOWN m = 1350 kg h = 45 m g = 9.8 m/s 2 UNKNOWN GPE = J FORMULA GPE = mgh FORMULA GPE = mgh SUBSTITUTION: GPE = 1350 kg 9.8 m/s 2 45 m Answer: 595,350 J c. A 1000 kg rocket that has an altitude of 625 m KNOWN m = 1000 kg h = 625 m g = 9.8 m/s 2 UNKNOWN GPE = J FORMULA GPE = mgh SUBSTITUTION: GPE = 1000 kg 9.8 m/s m Answer: 6,125,000 J 2. The Great American Dirt Corporation flies dirt around the United States. What is the gravitational potential energy of 10 containers of dirt that have a combined mass of 2600 kg, if the dirt is on a plane with an altitude of 1.5 km? (Hint: Convert the height to meters before solving.) KNOWN m = 2600 kg h = 1.5 km = 1500 m g = 9.8 m/s 2 UNKNOWN GPE = J SUBSTITUTION: PE = weight height = 2600 kg 9.8 m/s 2 FORMULA GPE = mgh 1500 meters = 38,220,000 J 3. A 5500 g bag is thrown out a window. If the bag has J of gravitational energy at its highest point, how far above the ground was it in meters at its highest point? (Hint: Convert the mass to kilograms before solving.) KNOWN GPE = 92.0 J m = 5500 g = 5.5 kg g = 9.8 m/s 2 UNKNOWN h = m SUBSTITUTION: GPE = J 5.5kg 9.8 m/s 2 Answer: m FORMULA h = GPE mg 2012, TESCCC 05/29/13 page 2 of 3

27 4. A skydiver has 360,000 J of gravitational potential energy as soon as they jumped out of the plane. If the skydiver jumped out of the plane at.6 km above the ground, what is the skydiver's mass in kilograms? (Hint: Convert the height to meters before solving.) KNOWN GPE = J h =.6 km = 600 m g = 9.8 m/s 2 UNKNOWN m = kg SUBSTITUTION: GPE = J 9.8 m/s m Answer: kg FORMULA m = GPE gh 2012, TESCCC 05/29/13 page 3 of 3

28 Roller Coaster Lab Background: In the course of a roller coaster ride, energy changes form many times. You may not have noticed the conveyor belt at the beginning, but in terms of energy, it is the most important part of the ride. All of the energy required for the entire ride comes from work done by the conveyor belt as it lifts the cars and the passengers. The energy from that initial work is stored as gravitational potential energy at the top of the first hill. After that, the energy goes through a series of transformations, or changes, turning into kinetic energy and then back into potential energy. A small amount of this energy is transferred as heat to the wheels and as vibrations that produce a roaring sound in the air. Materials (per group): roller coaster track masking tape marble stopwatch meter stick electronic balance Procedure: 1. Collect the materials listed above. Measure the length of the track in meters. Record the value in the analysis section below (#3). 2. Design a roller coaster with the first hill at a height of 1.20 meters. At least two more hills must follow. 3. Additionally, the roller coaster must demonstrate centripetal force in at least one location. Use the masking tape to tape your track to the cabinets/walls of the classroom. 4. Your marble must make it through the entire length of track without outside forces (you) acting on it. 5. The group that is able to design a roller coaster with the most total meters in height wins the class contest. Analysis and Calculations: 1. Define the following terms in roller coaster language (Relate it to the roller coaster.). a. Energy Conversions- b. Law of Conservation of Energy- c. Potential Energy- d. Kinetic Energy- 2012, TESCCC 12/06/12 page 1 of 3

29 2. Draw your final roller coaster (see last page). For each hill (top and bottom), include height, potential energy, and kinetic energy computations. 3. Calculate the average speed of the marble traveling through the roller coaster. Conduct at least three time trials for your calculation. Distance: Time Trial 1 Time Trial 2 Time Trial 3 Average Average Speed: 4. Calculate the acceleration of the marble traveling down the first hill of the roller coaster. Design a data table below that includes the information needed to calculate acceleration. Show your work for the calculation. Acceleration: 5. What is the relationship of height to potential energy and the resulting kinetic energy? 6. The equation for momentum is Momentum= Mass x Velocity. Predict how momentum would be effected if you used other marbles of different masses. 7. In an actual roller coaster, the conveyor belt does the work to create stored PE. What force did the work to create initial gravitational potential energy for your roller coaster? 2012, TESCCC 12/06/12 page 2 of 3

30 ROLLER COASTER DESIGN 2012, TESCCC 12/06/12 page 3 of 3

31 Roller Coaster Lab KEY Background: In the course of a roller coaster ride, energy changes form many times. You may not have noticed the conveyor belt at the beginning, but in terms of energy, it is the most important part of the ride. All of the energy required for the entire ride comes from work done by the conveyor belt as it lifts the cars and the passengers. The energy from that initial work is stored as gravitational potential energy at the top of the first hill. After that, the energy goes through a series of transformations, or changes, turning into kinetic energy and turning back into potential energy. A small amount of this energy is transferred as heat to the wheels and as vibrations that produce a roaring sound in the air. Materials (per group): roller coaster track masking tape marble stopwatch a meter stick electronic balance Procedure: 1. Collect the materials listed above. Measure the length of the track in meters. Record the value in the analysis section below (#3). 2. Design a roller coaster with the first hill at a height of 1.20 meters. At least two more hills must follow. 3. Additionally, the roller coaster must demonstrate centripetal force in at least one location. Use the masking tape to tape your track to the cabinets/walls of the classroom. 4. Your marble must make it through the entire length of track without outside forces (you) acting on it. 5. The group that is able to design a roller coaster with the most total meters in height wins the class contest. Analysis and Calculations: 1. Define the following terms in roller coaster language (Relate it to the roller coaster.). a. Energy Conversions- Energy conversions are what will happen as the energy moves along the roller coaster path. The energy of the marble will start w/ PE and eventually have all KE at the bottom. (Something similar is acceptable.) b. Law of Conservation of Energy- All of the energy that the marble starts out with will be conserved as it travels the roller coaster track. Some of the energy will be potential and kinetic, and some of it could change to heat energy. But what it starts with at the top will be what it has at the end. c. Potential Energy- Potential energy is the energy that it has at the highest point of the roller coaster. PE gets converted to KE as the marble moves towards the bottom. 2012, TESCCC 12/06/12 page 1 of 2

32 d. Kinetic Energy- Kinetic energy is the energy that the marble has because of its motion. It gets its KE because the PE is being converted as the marble gets closer to the finish position. 2. Draw your final roller coaster (see last page). For each hill (top and bottom), include height, potential energy, and kinetic energy computations. Drawings will vary based on student designs. 3. Calculate the average speed of the marble traveling through the roller coaster. Conduct at least three time trials for your calculation. Answers will vary based on student designs. Distance: Time Trial 1 Time Trial 2 Time Trial 3 Average Average Speed: 4. Calculate the acceleration of the marble traveling down the first hill of the roller coaster. Design a data table below that includes the information needed to calculate acceleration. Show your work for the calculation. Answers will vary based on student designs. Acceleration: 5. What is the relationship of height to potential energy and the resulting kinetic energy? The higher the position of the marble on the roller coaster means there will be less KE. As the height of the marble goes up, the KE goes down. As the marble goes down, the higher the KE goes. 6. The equation for momentum is Momentum= Mass x Velocity. Predict how momentum would be effected if you used other marbles of different masses. The greater the marble, the greater the momentum would be. It would also mean that there would be a greater PE to start and greater KE when it is at the end. 7. In an actual roller coaster, the conveyor belt does the work to create stored PE. What force did the work to create initial gravitational potential energy for your roller coaster? The force of the arm lifting the marble to the top of the roller coaster track creates initial GPE. 2012, TESCCC 12/06/12 page 2 of 2

33 Performance Indicator Instructions KEY Performance Indicator Given a specific example, create a chart that shows energy s journey from potential to kinetic. In a written summary, explain the chart, and describe how the energy was ultimately conserved. (I.2E; I.5A, I.5B, I.5D) 1C; 2E; 3D; 4D; 5B Materials: poster board (or other paper for charts, per group) markers (per group) Instructional Procedures: 1. On Day 9, explain to students they will need to pick five points on their group s roller coaster and determine the amount of total energy, kinetic, and potential energy at each of the locations they chose. 2. Inform students of the following: The points must include the highest point of the roller coaster, the top of a loop, and the end of the roller coaster, as well as two other points that the students choose. Students must create a chart that shows how the energy transitions from the beginning of the roller coaster to the end of the roller coaster, using the five points as reference and calculation points. In their science notebooks, each individual must write a summary explaining the chart and describing the energy transformation and, ultimately, how energy was conserved. Students should show all calculations in their science notebooks. On Day 10, students will display their group s chart to the class. Each group will give a verbal explanation including the energy at the five points chosen and how energy was transformed and conserved as the marble moved through the roller coaster. Each person in the group is required to participate in the presentation. Instructional Notes: You may want to review KE and PE formulas again or instruct students to use their notes to help complete the charts and summaries. Science Notebooks: Students use their notes to review and reinforce appropriate use of formulas. 2012, TESCCC 05/29/13 page 1 of 1