Lesson: Exploring Energy: Kinetic and Potential

Contributed by: RESOURCE GK-12 Program, College of Engineering, University of California Davis

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Energy exists in many different forms.
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Summary

Students learn about kinetic and potential energy, including various types of potential energy: chemical, gravitational, elastic and thermal energy. They identify everyday examples of these energy types, as well as the mechanism of corresponding energy transfers. They learn that energy can be neither created nor destroyed and that relationships exist between a moving object's mass and velocity. Further, the concept that energy can be neither created nor destroyed is reinforced, as students see the pervasiveness of energy transfer among its many different forms. A PowerPoint® presentation and post-quiz are provided.

Engineering Connection

A firm understanding of energy types and energy conversion is essential to understanding the different forms of energy (and energy transfers) so common in our everyday lives, as well as a basis for comprehending more advanced concepts in engineering, physics, renewable energy, electrical generation and other fields. It takes energy to power vehicles, but the same task may be performed by energy in different forms (gasoline, lithium-ion batteries, etc.), as designed by engineers to meet specific functional requirements.

Learning Objectives

After this lesson, students should be able to:

  • Explain the relationship between a moving object's kinetic energy and its mass and velocity.
  • Identify different forms of kinetic and potential energy.
  • Relate daily life experiences to different types of energy.

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Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Construct, use, and present arguments to support the claim that when the kinetic energy of an object changes, energy is transferred to or from the object. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
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Introduction/Motivation

In the previous lesson, we learned that energy is the ability to make things happen. Energy is in use everywhere and comes in many different forms. It can be stored and then employed to do things for us. In fact, all types of human activities require the input of energy. Gasoline is necessary to power automobiles, ships and airplanes so that we can travel long distances. Electricity powers light bulbs so we can continue to study, work and have fun after dark. Fireplaces, electrical heaters and gas furnaces provide warm indoor air so we can survive when the weather is freezing. And food, grown with the energy from the sun, is our fundamental source of energy to support our lives. Everywhere you look, in all sorts of different forms, energy is present and important in our daily lives.

Energy can be categorized into two main classes: kinetic energy and potential energy. Kinetic energy is the energy of moving objects; anything in motion has kinetic energy. It is calculated as KE = (1/2) x mass x speed2. The heavier an object, the more kinetic energy it has when in motion. If an object's mass is doubled, its kinetic energy under the same speed is also doubled. The faster an object moves, the more kinetic energy it has. If an object's speed is doubled, its kinetic energy is quadrupled.

Gravitational energy, chemical energy, elastic energy and heat/thermal energy are all categorized as stored energy—also called potential energy. Energy can be stored in chemicals (food, batteries), height (gravitational), elastic stretching, etc. Gravitational energy is the energy that is stored due to the height of objects. Gravity is the force that pulls things down to Earth. The higher an object, the more gravitational energy it has. Often, gravitational energy (a form of potential energy) is converted to kinetic energy, such as when objects drop off cliffs or roll down ramps. Chemical energy is the energy that is stored in the chemical bonds of molecules. This energy is released during chemical reactions. Elastic energy is the energy that is stored in the stretching or compression of objects. Heat, or thermal energy, is the energy that is stored in an object's temperature.

One of the most important concepts about energy is that energy can be neither created nor destroyed; it can only be transferred, or converted, from one form to another. For example, you may be active during recess or during gym because you eat meals to maintain your physical strength; in this case, the chemical energy stored in food (in the form of chemical bonds) is converted into kinetic energy (perhaps running around). Electrical energy is converted into light that we use to see in the classroom; it also powers the air conditioner or heater so we can study in a comfortable air temperature. Can you think of some more examples of energy conversion from one form to another?

(Continue by showing the presentation and delivering the content in the Lesson Background section.)

Lesson Background and Concepts for Teachers

Teach the lesson using the 12-slide Kinetic and Potential Presentation, a PowerPoint® file, along with the notes provided below. The presentation is animated, so clicking brings up the next image, text or slide. The presentation contains review questions and activities that ask students to use their new energy knowledge. The associated activity also provides opportunities to discuss and review key concepts.

(Slide 2) As a class, verify students' understanding of concepts learned in the previous lesson by asking them to define the following terms: energy, kinetic energy, potential energy and energy transfer.

(Slides 3-5) The kinetic energy of a non-rotating solid object is given by: KE = (1/2) x mass x velocity2. Use these slides to teach students 1) that two quantities, mass and velocity, define the kinetic energy of an object, and 2) how KE varies with mass and velocity. The second concept may be difficult to grasp. It is helpful to graph the relationship on the classroom board or show students a simulation to demonstrate the relationship, such as The Ramp from PHET Interactive Simulations at http://phet.colorado.edu/en/simulation/the-ramp.

(Slides 6-10) Energy can be stored in many forms. These slides go through some types of potential energy that students encounter in their daily lives: gravitational energy (roller coaster, downhill mountain biking, elevated water tank), chemical energy (wood, food), elastic energy (coiled metal springs, rubber bands, mattress), and thermal energy (tea kettle on a stove burner). Ask students to think of other examples for each type of potential energy.

(Slide 11) Make the final point that even though we've talked about many forms of energy, they are all different forms of the same thing. Remind students that energy can be converted from one form to another.

(Slide 12) Using the writing prompt on this slide (and description in the Assessment section), assign students to write about three fictional superpowers, and then read them to the class. Make sure students communicate using the energy terms learned in the lesson. Then conclude by administering the post-quiz.

Vocabulary/Definitions

chemical energy: Energy that is stored in the chemical bonds of molecules. This energy is released during chemical reactions.

elastic energy: Energy that is stored in the stretching or compression of objects.

energy: The ability to make things happen. More advanced definition: The ability to do work.

gravitational energy: Energy that is stored in the height of objects. Gravity is the force that pulls things down to Earth. The higher an object, the more gravitational energy it has. Often, gravitational energy (a form of potential energy) is converted to kinetic energy to make things move fast.

kinetic energy: The energy of moving objects. Anything in motion has kinetic energy. The faster an object moves, the more kinetic energy it has.

potential energy: Energy that is stored and can be used when needed. Energy can be stored in chemicals (food, batteries), height (gravitational), elastic stretching, etc.

thermal energy: Energy that is stored in an object's temperature. Heat.

Associated Activities

  • Making Moon Craters - During a class demonstration, a weighted plastic egg is dropped into a tray of flour from different heights as a way to model asteroids hitting the moon's surface. By watching the potential-to-kinetic energy transfer and measuring the resulting impact craters, students directly see the effect that the height and mass of an object has on the overall energy of that object. Students learn the kinetic and potential energy equations, make predictions, and collect and graph data.

Attachments

Assessment

Pre-Lesson Assessment

Definition Review: To verify students' understanding of concepts learned in the previous lesson, ask them to define the terms listed on slide 2 of the Kinetic and Potential Presentation: energy, kinetic energy, potential energy and energy transfer.

Post-Introduction Assessment

Discussion Questions: Use class discussions and student writing assignments to evaluate student knowledge. Throughout the Kinetic and Potential Presentation are many opportunities for quick assessments of understanding. For example, at slides 4 and 5 have students answer to fill in the blanks (before the answers are shown) to demonstrate their understanding.

Lesson Summary Assessment

Superpower Writing: Use the writing prompt on slide 12 to assess learning from this lesson: You are a superhero! You have three energy superpowers! Write a paragraph explaining: What are your superpowers? How do you use them? What kind of energy do they use? Require students to use the energy terminology learned in the lesson (and provided in a word bank on the slide). After students are done, give them time to share their answers with the class.

Post-Quiz: In addition, administer the Kinetic and Potential Post-Quiz to assess students' understanding of the relationship between mass, velocity and the kinetic energy of an object, as well as their ability to identify examples of various types of energy.

Contributors

Eric Anderson, Jeff Kessler, Irene Zhao

Copyright

© 2014 by Regents of the University of Colorado; original © 2013 University of California Davis

Supporting Program

RESOURCE GK-12 Program, College of Engineering, University of California Davis

Acknowledgements

The contents of this digital library curriculum were developed by the Renewable Energy Systems Opportunity for Unified Research Collaboration and Education (RESOURCE) project in the College of Engineering under National Science Foundation GK-12 grant no. DGE 0948021. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: May 18, 2017

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