Energy Conversion Chart Homework Answers

Learning Objectives

After this lesson, students should be able to:

  • Describe at least three examples of how energy is converted from one form to another.
  • Demonstrate and diagram the conversion of energy into usable forms using a flow chart.
  • State the law of conservation of energy.
  • Identify five forms and two states of energy.
  • Identify the form and state of energy in everyday items as we use them to do useful work.

More Curriculum Like This

Energy Forms and States Demonstrations

Demonstrations explain the concepts of energy forms (sound, chemical, radiant [light], electrical, atomic [nuclear], mechanical, thermal [heat]) and states (potential, kinetic).

Exploring Energy: Energy Conversion

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Energy Conversions

Students evaluate various everyday energy conversion devices and draw block flow diagrams to show the forms and states of energy into and out of the device.

To Heat or Not to Heat?

Students are introduced to various types of energy with a focus on thermal energy and types of heat transfer as they are challenged to design a better travel thermos that is cost efficient, aesthetically pleasing and meets the design objective of keeping liquids hot.

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 (

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.

NGSS: Next Generation Science Standards - Science
  • Construct an argument supported by evidence for how increases in human population and per-capita consumption of natural resources impact Earth's systems. (Grades 6 - 8) Details...View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
Common Core State Standards - Math
  • Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation. (Grade 6) Details...View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
  • Use variables to represent quantities in a real-world or mathematical problem, and construct simple equations and inequalities to solve problems by reasoning about the quantities. (Grade 7) Details...View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
International Technology and Engineering Educators Association - Technology
National Science Education Standards - Science
  • Energy is a property of many substances and is associated with heat, light, electricity, mechanical motion, sound, nuclei, and the nature of a chemical. Energy is transferred in many ways. (Grades 5 - 8) Details...View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
  • Electrical circuits provide a means of transferring electrical energy when heat, light, sound, and chemical changes are produced. (Grades 5 - 8) Details...View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
  • In most chemical and nuclear reactions, energy is transferred into or out of a system. Heat, light, mechanical motion, or electricity might all be involved in such transfers. (Grades 5 - 8) Details...View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
New York - Science
  • Construct an argument supported by evidence for how increases in human population and per-capita consumption of natural resources impact Earth's systems. (Grades 6 - 8) Details...View more aligned curriculum... Do you agree with this alignment? Thanks for your feedback!
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Energy exists in many forms all around us. The development of our modern society has been accomplished because scientists and engineers have learned to capture some of that energy and transform it into ways to do useful work. The conversion of energy from a chunk of coal into steam and then into mechanical engines that could do heavy work was a critically important role for engineers in the 19th century that helped to start the industrial revolution. An engineer must know where to "find" energy resources and then how to convert them into forms that are more useful for all of the machines and gadgets we use in our daily lives. Look around this room, what tools or devices are using energy? Light fixtures are a good example. They convert electrical energy into light (radiant) energy. What about this cup of water (hold up a cup of water), does it have energy? It has a state of energy called potential energy because it is held up at an elevation. If the water is poured into a pail, the potential energy is released as the water now is moving with some velocity. This is a kinetic state of energy.

The goal of this class is to explore some critical terms that are needed for energy – forms of energy and states of energy. Tomorrow, that information will be used as we evaluate several items, like the lights in this class, to see how they convert energy from one form to another.

Lesson Background and Concepts for Teachers

1. Energy can be neither created nor destroyed, but converted from one form to another. This can be represented as the first law of thermodynamics.

2. Energy can be classified by its form or state.

3. The forms of energy defined in NYS educational standards include: sound, chemical, radiant (light), electrical, atomic (nuclear), mechanical, thermal (heat). Remembered as "SCREAM Today"

  • Sound – from vibration of sound waves
  • Chemical (fuel, gas, wood, battery)
  • Radiant (light) (note – this is part of the broader "electromagnetic" group)
  • Electrical energy (electrons move among atoms, as in the conductive wire of an electrical cord)
  • Atomic (nuclear, from nucleus of atom)
  • Mechanical (walk, run)
  • Thermal (heat, such as rubbing hands together)

4. The two states of energy are potential and kinetic

  • Potential (stored energy due to elevation): PE = mass*gravity*height
  • Kinetic (energy in motion): KE = 1/2*mass*velocity2

5. Energy is stored in a variety of ways and must be released to do useful work

6. Energy can be converted to useful forms by various means, we often convert the form of energy to make it more useful to us. For example, we transform chemical energy in gasoline into mechanical energy to move an automobile.

7. Energy and its conversion between forms can be expressed quantitatively.

8. When converting energy, a significant fraction of that energy can be lost from the system (in the form of heat, sound, vibration, etc.). But of course energy is never really lost. "Lost" in this context means that it is not recovered for effective use by humans or machines.


block process flow diagram: A physical representation of inputs and outputs of a process, used by engineers.

chemical energy: Energy stored within chemical bonds.

combustion : The process of burning organic chemicals to release heat and light.

conservation : Careful use of resources with the goal of reducing environmental damage or resource depletion.

efficiency: Ability of a process or machine to convert energy input to energy output, efficiency is always less than 100% in real processes. Efficiency of a system can be quantified as the ratio of the useful output energy (or power) to the input energy (or power).

electrical energy: Energy made available by the flow of electric charge through a conductor.

energy conversion: Transformation of one form of energy into another, usually to convert the energy into a more useful form.

first law of thermodynamics: Energy can neither be created nor destroyed.

form of energy : Forms of energy include heat, light, electrical, mechanical, nuclear, sound and chemical.

heat : A form of energy related to its temperature. (thermal energy)

input: Matter or energy going into a process.

kinetic energy: Energy of motion, influenced by an objects mass and speed.

mechanical energy: A form of energy related to the movement of an object.

nuclear energy: (atomic) Energy produced by splitting the nuclei of certain elements.

output: Matter or energy coming out of a process.

potential energy: Energy that is stored and that comes from an object's position or condition.

state of energy: States of energy include kinetic and potential.

Associated Activities

  • Energy Forms and States Demonstrations - Demonstrations explain the concepts of energy forms (sound, chemical, radiant [light], electrical, atomic [nuclear], mechanical, thermal [heat]) and states (potential, kinetic).
  • Energy Conversions - Students evaluate everyday energy conversion devices and draw block energy flow diagrams of them after seeing a teacher demo of a more complicated example. They identify the useful energy forms and the desired output of the device, and the forms that are not useful for the intended use. They learn about the law of conservation of energy and efficiency.


Conversion Activity Student Worksheet (doc)


Post-Introduction Assessment: Plan on a lot of dialogue and student participation in the first day of this lesson. Use the many probing questions included in the forms and state demonstration activity to assess if students understand the concepts.

Homework: Use the turned-in student activity worksheet completed during the conversion activity as a means of assessing if students correctly identified the forms involved in each conversion process and can include those forms correctly in a block diagram form.

Worksheet & Quiz: Have students complete the activity worksheet and discussion questions and turn them in. The quiz after Lesson 5 also includes concepts from this lesson.

Practice Problems:

  • If the mass of an object is 10 kg, and it is dropped from a height of 5 m, what is its potential energy? (Answer: PE=(10 kg)(9.8 m/s2)(5 m)=490 Nm) (A Nm (newton-meter) is equivalent to a (kg*m2)/s2)
  • If the kinetic energy of an object is 100 Nm, and its velocity is 10m/s, what is the mass of the object? (Answer: m=2KE/v2 =2*100 Nm/〖10 m/s〗2 =2 kg)


Biggs, A., Burns, J., Daniel, L.H., Ezralson, C., Feather, R.M., Horton, P.M., McCarthy, T.K., Ortleb, E., Snyder, S.L., Werwa, E. Science Voyages: Exploring Life, Earth and Physical Science, Level Red., Glencoe/McGraw Hill: New York, 2000.

Intermediate Level Science Core Curriculum, Grades 5-8, New York State Education, Department, accessed December 31, 2008.

Other Related Information

This lesson was originally published by the Clarkson University K-12 Project Based Learning Partnership Program and may be accessed at


Susan Powers; Jan DeWaters; and a number of Clarkson and St. Lawrence University students in the K-12 Project Based Learning Partnership Program


© 2013 by Regents of the University of Colorado; original © 2008 Clarkson University

Supporting Program

Office of Educational Partnerships, Clarkson University, Potsdam, NY


This lesson was developed under National Science Foundation grants no. DUE 0428127 and DGE 0338216. 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: January 3, 2018


Students participate in many demonstrations during the first day of this lesson to learn basic concepts related to the forms and states of energy. This knowledge is then applied the second day as students assess various everyday objects to determine what forms of energy are transformed to accomplish the object's intended task. Students use block diagrams to illustrate the form and state of energy flowing into and out of the process. This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering Connection

Energy exists in many forms all around us. Engineers have determined how to capture and release that energy in forms that are most useful to create heat where required and the work done in many engineered devices. Process flow charts that show the inflow and outflow of energy through a process are one tool that engineers use to help design and evaluate different systems and processes.

  • Using Einstein's famous equation E = mc2, show that when 4 protons fuse into 1 helium nucleus via the proton-proton cycle, about 4.14 x 10-12 Joules of energy is released. (The mass of one individual proton is about 1.6725 x 10-27kg; the mass of one helium nucleus is about 6.644 x 10-27 kg.)

    The difference in the masses of the Helium nucleus and the 4 protons is 4.6 x10-29kg.

    (4 x 1.6725 x 10-27kg) - 6.644 x 10-27kg = 4.6 x10-29kg

    E = (4.6 x10-29kg)x( 9.0x1016 m2/s2) = 4.14x10-12 Joules

    (recall one Joule is a kgm2/s2)

  • The total luminosity (energy radiated per second) of the sun is about 3.85 x 1026 J/s. How many nuclei of helium are being created per second?

    The number of He nuclei produced each second corresponds to the number of fusion reactions occuring (as each reaction produces one He nucleus). Divide the energy output of the Sun by the energy of one fusion reaction to find out how many reactions per second are required to power it, and we'll have our Helium count as well.

    (3.85x1026 J/s)/(4.14x10-12 J/reaction) = 9.29 x1037 reactions (Helium nuclei)/s.

  • What percentage of the hydrogen mass is converted into energy via fusion?

    The proportional change in mass is the actual change 4.6x10-29kg (note that we can write it as .046 x10-27 kg so that it more easily cancels), divided by the original mass of 4x1.6725x10-27kg = 6.690 x10-27kg.

    (.046 x10-27kg)/(6.690 x10-27kg) = 0.0068

    which expressed as a percentage is 0.68 % ( 0.7 % for those of us who round)

  • How much mass in the Sun is being converted into energy every second?

    We can solve this by dividing the given Luminosity by c2(A) or by multiplying the values we calculated for reactions per second and mass-loss per reaction (B). Either approach gives us 4.27x109kg.


    E/c2 = m

    (3.85 x 1026J)/(9.0 x 1016m2/s2) = 4.27x109kg


    (Mass converted/reaction)x(# of reactions/sec) = Mass converted/sec

    (4.6x10-29kg)x(9.29 x1037 reactions/sec) = 4.27x109kg/s

  • The Sun has a mass of 1.989 x 1030kg. Only 10% of that mass is available for hydrogen fusion in the core. Show that the Sun's lifetime on the main-sequence (how long it burns hydrogen in the core) is 10 Billion years.

    The Hydrogen fusion reaction only converts 0.68% of the reaction mass into energy, so the Sun is actually "using" a tiny fraction of that 10 percent. The total converted will be (0.1x0.0068) = 6.8x10-4 times its total mass

    6.8x10-4 x 1.989 x 1030kg = 1.35x1027kg

    (by E = mc2 this is a total of 1.21x1044 Joules produced!). .

    Since we know both the mass consumption rate and the energy production per second, we can determine the Sun's lifetime with either by dividing mass or energy rates.

    (1.35x1027kg)/(4.27x109kg/s) = 3.15 x 1017sec


    (1.21x1044J)/(3.85 x 1026J/s) = 3.15 x 1017sec

    As there are about 3.15x107 seconds in a year the Sun has 1x1010 - or 10 Billion years to cook.

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