Grade: 9-12

Content Area: Science

Course Name: Physics

Description of Unit: During this unit students will examine the conservation of energy. Transformations between type will be explored as well as the relationship between energy and momentum in collisions.

Approximate Time Needed: 9-11 days

Lesson

Duration

Supporting Target

Resources

Assessment

1

1-2 days

I can explain and calculate the work, power, potential energy and kinetic energy involved in objects moving under the influence of gravity and other mechanical forces.

I can calculate and explain the energy, work and power involved in energy transfers in a mechanical system.

I can explain and calculate the work, power, potential energy and kinetic energy involved in objects moving under the influence of gravity and other mechanical forces.

I can describe and calculate the quantity of heat transferred between solids and/or liquids, using specific heat, mass and change in temperature.

Intro Energy

Energy worksheet

Pre

2

1 day

I can calculate and explain the energy, work and power involved in energy transfers in a mechanical system.

I can explain and calculate the work, power, potential energy and kinetic energy involved in objects moving under the influence of gravity and other mechanical forces

Horsepower Lab

Jump Energy Lab

Formative

3

1 day

I can calculate the kinetic and gravitational potential energy in a system.

I can evaluate the loss of energy from a system.

I can use conservation of momentum and conservation of energy to analyze an elastic collision of two solid objects.

Conservation of Energy Video Lab

Formative

4

1 day

I can describe and calculate the quantity of heat transferred between solids and/or liquids, using specific heat, mass and change in temperature.

Calorimetry Lab

Formative

5

2 days

I can calculate and explain the energy transferred in a mechanical system.

I can describe the heat that is transferred between objects using conduction, convection and radiation.

Energy Assessment - Brake Design

Summative

6

1-2 days

I can explain energy transfers in terms of the conservation of energy.

Fictional Physics - Perpetual Motion Machines

Student Worksheet

Summative

7

2 days

I can calculate the work involved in energy transfers.

Optional Project - Egg drop

Formative/Summative

Activity

Notes to Instructors

Intro Energy 

Slide 2: The picture is given to aid in the discussion on what forces will cause work. If we connect this back to a person walking with constant motion, the applied force is causing work to be done in moving forward but the friction force is taking that energy away. The result is no net work being done. This is a difficult concept for students because they know that when they walk, they are using energy. This will be explained further as you discuss conservation of energy.

Slide 3: The formulas that are on this slide are connected to the Energy worksheet. After discussion of this slide, take a break with the students to complete the data collection for the Exploration and questions 1 - 5.

Slide 4: Show the video. It will connect to the last slide and introduce the concept that work relates to kinetic energy.

Slide 5: The connection of work to gravitational potential energy is defined. Go back to the Exploration and complete questions 6 - 9. The remaining questions are review back to the last unit on momentum.

Slide 6: Show the video and follow it up with the discussion questions.

Slide 7: The video is a demonstration of a Hero’s engine. You can create one out of a pop can to do as a live demo if you would prefer. Follow up the video with the discussion questions.

Slide 8: The final formulas are the ones connected to heat. After discussion these, the students can work on the Energy worksheet.

Time: 40 minutes

Energy worksheet

1. W; The football is moving in the direction of the applied force.

  N; There is no displacement; W = F * 0 m, W = 0 J

  N; The applied force is 90º from the displacement; W = F * d * cos 90; W = 0 J

 W; The car is moving in the direction of the applied force.

 N; No physical force is applied.

2. 2,400 J; 340 J

3. 4,100 J

4. 0.4 m

5. 4.3 s

6. 180 W

7. 190 W

8. 36,000 W

9. 110,000 J

10. 17 m/s

11. 2,100 J

12. 8 kg

13. 6 m

14.

  0.15 m

15. 7,900 J

16. 0.12 kg

17. 390 J/kg * K

18. copper

19. 61,500 J

20. 20.7 kg

21. 17ºC

22. 106,000 J

Horsepower Lab 

The work done running or walking up a flight of stairs can be calculated by multiplying the weight of the person in Newtons times the height in meters. Using a stopwatch to measure the time to get up the steps allows for a power calculation. Materials needed: metric ruler and stopwatch.

Jump Energy Lab

Teacher’s Guide

Materials: Meter Stick

In this lab students take data on a jump that they perform in class. Students will need to use their mass, but they can just make one up(that is reasonable) if they don’t know it or don’t want ti share it with you. The activity uses the conservation of energy to go back and forth between different quantities of energy to solve problems.

Time: 45 minutes

Conservation of Energy Video Lab

Purpose: This lab is used to help students better understand the concepts of energy. Students will be using Direct Measurement Videos - Energy to collect data and perform calculations. Students will be able to use Quicktime as done in similar activities. Directions for downloading the videos to the student’s computers is on the page. A discussion on the number of significant figures could be part of this activity as well to establish certainty in measurements.

Ipad Option: You can download the videos and put them in a dropbox to share with the students. Once they have the video saved in their camera roll, data can be collected by opening the video and scrolling the playhead at the top. Students will have to watch the frame and may need to make notes on which one they are on.

A Pendulum: This video shows a pendulum being released. The height after the release is about 38.1 cm for a GPE of 0.0933 J. It takes about 37 frames at 960 fps at the bottom for a velocity of 2.59 m/s and 0.841 J of KE. The return yielded about 37.5 frames for 2.56 m/s and 0.0819 J at the bottom and 37.4 cm for 0.0916 J at the top. The pendulum data does not support the conservation of energy, but the system is not closed. Examples of where the energy may go include air resistance and friction at the pivot point of the string.

Roller Coaster 1: The train’s average mass is 5070 kg which will give it a GPE of 3,130,000 J. The velocity at the bottom is about 104 m/s for 27,500,000 J. The energy is not conserved. The missing piece is the velocity at the top of the hill. If the coaster did not have KE at the top, it would not go over the hill. As an extension, student’s could find the speed of the train as it passes over the top of the hill.

Ballistics Pendulum: Sample data for this could be 76.0 cm for pendulum length, 35.5° for maximum angle. The GPE would be equal to the KE just after the ball hits the pendulum so conservation of energy can be used and the masses cancel to give a velocity of 1.66 m/s. Example velocity exiting the cannon is 81.1 m/s. The masses of both the ball and pendulum are given on the site and can be used to check the conservation of energy and momentum. Energy is lost in the collision due to the work required to stop the ball in the pendulum.

Time: 30-40 minutes.

Calorimetry Lab

Purpose: This activity examines the transfer of heat from warm objects to cooler objects. Calculations are made in calories, but could be made in joules.

Procedure notes:

1. Use of two thermometers may be more efficient.

2. QL = GG 

4. QL = GG

5. The ice and liquid water should be in equilibrium after several minutes. (0oC)

6. QL / g = ∆T for the hot water

7. QL /g of ice should be considerably greater than #6.

8. Some of the heat goes into melting the ice without any ∆T.

9. QL = GG, Heat transfers until objects reach equilibrium temperature. Heat goes into cold objects.

10. Some heat could go into the air or the cup and not be measured.

Time: 50 minutes

Energy Assessment - Brake Design

Purpose: For students to apply what they have learned about concepts of energy in physics and relate them back to a common system - brakes.

For this project students will create a presentation. Depending on your learning environment, these presentations can be with partners, presented in class, share screen-casts of presentations given at home, etc. Whether you want to have the student use Powerpoint, Google Presentations, Prezi or something else entirely is completely up to you. The time to complete will depend on how much in class versus how much out of class time you give the student.

A grading rubric has been included.

Time: 90-135 minutes

Fictional Physics -

Student Worksheet

Purpose: For students to think critically about perpetual motion machines by examining forces and energy changes in the system.

Debunking a perpetual motion machine can be a difficult task, which is why they are so pervasive! It should be completely ok for students to seek outside resources when trying to make an explanation for why they do not really work. This being said, make sure the students are putting what they learn into their own words, and of course citing properly. This project will be most powerful when the results of what students find is shared. So at the very least you should plan to have a class discussion once the project is complete. For alternatives and additions to this, you could have students:

• Give a presentation
• Make a video sales pitch to be shared with the class.
• Make a “working” model of the device.

Time: 45 minutes plus - depending on how you choose to use it.

Optional Project - Egg drop

Purpose: This project is a classic! Students really enjoy watching their devices survive and fail! This project could either be done mid-unit or at the unit completion. Students use what they know about conservation of energy to calculate what distance is needed to stop an egg over to not break it. I would suggest only using two class days to for this project. One to explain the project and take pre-design measurements and then let students have a chance to work on designs and ask questions. Then one day to test the devices. Construction of the devices should be done at home. So perhaps start it on the day after the introduction and complete it on the last day of the unit.

Time: 90 minutes