3.3 — Energy: Swinging – Part II

App Features

Using the energy lens students will:

• Use previously recorded performances.
• Create a path.
• Add height and mass.
• Adjust ground height.

Expected Activity Time

• Total Activity Time: 45 minutes
• Introduction: 20 minutes
• Investigation: 20 minutes
• Discussion: 5 minutes

Materials and Prep

• iPad with the Playground Physics app
• Videos created by students in the app
• (Students should have done this as part of Lesson 3.2 – Fun with Energy). If you skipped Lesson 3.2, please have students record a video of someone in their group swinging.)
• Worksheet: Energy: Swinging – Part II

Activity

Introduction: 20 minutes

• Tell students that when scientists study the world they need to have standard ways of describing things so that other scientists can understand their data and analysis. Tell students that today they are going to be learning standard ways to describe energy so that as a class they can begin talking about the patterns they see in the energy of someone swinging and know that they are all talking about the same thing.
• Ask students what the word energy means. Take student suggestions and write them on the board. There are many types of energy so students’ answers will be varied. Students will likely think about the types of energy that power things first. They may also talk about food giving their body energy.
• Once students’ ideas are on the board, ask them if any of the types of energy they have mentioned can change forms. Can one type of energy be converted to another type? As a class, come to the consensus that energy can be converted from one form to anther. If students are having trouble with this idea, use a vacuum cleaner as an example. When you plug a vacuum cleaner into the wall and turn it on, the vacuum cleaner turns electrical energy into mechanical energy to make it move. You also have heat and sound energy that is given off by the vacuum cleaner.
• Tell students that these types of energy can be classified into two large categories – potential energy and kinetic energy. Kinetic energy is the energy of motion, whereas potential energy is stored energy. Energy can be transferred between kinetic energy and potential energy.
• A great example to help students visualize the transfer of energy between kinetic and potential is a rollercoaster. On the way up a hill, the rollercoaster is moving so it is using kinetic energy. Once it reaches the top of the hill, the rollercoaster has a large amount of potential energy that it has gained due to the height of the rollercoaster car above the ground. As the rollercoaster starts to go back down the hill, its kinetic energy increases again and its potential energy decreases.
• Tell students that they are going to be able to track kinetic and potential energy while swinging through the use of the app. Ask students what information might be important to document when talking about the energy of an object. Take students suggestions and record them on the board.
  Share with students that when talking about the energy of an object in physics, we want to make sure to document and record the object’s speed, the vertical distance of the object from the ground, and the mass of the object.
• As a class, go through the three examples in the “Recognizing Energy” portion of the worksheet so that students are familiar with where to find the information displayed in the app and gain experience describing energy. If possible, project these worksheets at the front of the class and have students follow along on their own copies.

Investigation: 20 minutes

• Tell students that today they are going to analyze the video they recorded in their group of someone swinging.
• Pass out iPads to groups of students. Students should be working in the same group and should use the same iPad so that they have access to the videos their group recorded.
• Have students pull up a video of someone in their group swinging. Each group should create a path of the motion by placing dots on the person swinging as they move back and forth.
• Have students open the graph drawer so they can see the white arrow that points in the direction that the object they are tracking is moving. (In this case, the students are tracking the movement of the person swinging so the arrow will change directions based on the direction the swing is moving.) Turning on the slow motion feature (turtle button) may make it easier for students to see the direction change in relation to the video they are watching.
• Once students have annotated their videos, have them describe the energy of the person swinging by completing the “Describing Our Own Energy” section of the worksheet.

Discussion: 5 minutes

• Once students have completed the worksheet, ask them if there is any data that is important when thinking about the energy of the person swinging that was not included in the questions on the worksheet. Allow time for students to share their ideas to this question and to share anything else that surprised them about the energy involved with swinging in their video.
• Remember to check the Parking Lot of questions at the end of the class period. Remove any questions that have been answered and have students add any new questions that may have come up.

Answer Key

Recognizing Energy

3.
a) Speed: 0.1 mps
b) Height from ground: 0.98 m
c) Potential energy: 478.75 J
d) Kinetic energy: 0.1 J
e) Direction of motion (draw an arrow): ↑

4.
a) Speed: 0.2 mps
b) Height from ground: 1.96 m
c) Potential energy: 959.18 J
d) Kinetic energy: 1.2 J
e) Direction of motion (draw an arrow): ↙

5.
a) Speed: 3.6 mps
b) Height from ground: 1.26 m
c) Potential energy: 617.73 J
d) Kinetic energy: 316.2 J
e) Direction of motion (draw an arrow) : ↙

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