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Back and Forth

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Updated on Feb 07, 2012

Grade Level: 7th; Type: Physics/Physical Science

To determine whether we can change from potential energy to kinetic energy and from kinetic to potential?

  • How do we define energy?
  • What is potential energy?
  • What is kinetic energy?
  • List examples of potential and kinetic energy.
  • What is the Law of Conservation of Energy?
  • What are the practical applications of The Law of Conservation of Energy?

Data Chart: Reproduce This Chart for Recording Your Observations


Distance Travelled in metrics


On the information level, this experiment serves to acquaint students with basic information on kinetic and potential energy. First and foremost the term energy is defined as the property of an object that allows it to produce change in the environment or in itself.Kinetic energy is defines as the energy an object has because of its motion as opposed to potential energy which is the energy an object has stored in it that can cause it to move. Potential energy is also viewed as energy of position. An object in an elevated position, such as a car on a hill has potential energy. If the brakes fail the car will roll down the hill using and releasing its potential energy and converting it in to kinetic energy. An object in a stretched or compressed position has potential energy. For example the stretched bow of an archer demonstrates this. The archer first pulls the bow string towards himself, storing the energy in the bow, when he releases the bow, the energy of position has just been trans formed into the energy of motion, namely kinetic energy and the arrow moves forward. We use kinetic energy when we wind the spring on a mechanical toy. Each wind or turn of the key adds more tension on the spring giving us more potential energy. When we release the toy, the stored potential energy now changes to kinetic energy and the toy takes off.This project focuses on the conservation of energy. The question you will address will give you the evidence you need to answer your original question, can one kind of energy be converted into the other and is the reverse true?Good luck!

This science fair experiment also serves to acquaint students with the essential processes of sciencing such as the importance of the use of a control, of identifying dependent and independent variables, of data collection, of pictorial and or graphic presentation of data and of being able to make better judgments as to the validity and reliability of their findings.They take on the role of scientists and in the process they learn to act as one.

  • Cylindrical
  • Cardboard oatmeal box with cover
  • Masking tape
  • Rubber bands
  • Lead sinker or a washer
  • Metric ruler
  • Soap
  • Water
  • Paper towels
  • Scissors
  • Camera (If you want to take pictures as you roll along)

Do not forget those safety goggles!

  1. Gather all the materials you will need for your experiment. These include: a cylindrical, cardboard oatmeal box with cover, a hole punch, masking tape, rubber bands, a lead sinker or a metal washer, a metric ruler, and a pair of scissors. Do not forget those safety goggles!
  2. Reproduce the data chart provided on the next page so that you can readily record your findings.
  3. Put on your safety glasses. Using the hole punch, make two holes in the bottom of the oatmeal box and two holes in the lid.
  4. Take each rubber band and cut each one so that you now have two long pieces of rubber.
  5. Now thread one end of each rubber band through the hole at the top thread the ends of one rubber band through the holes in the of the sinker.
  6. Take off the lid from the oatmeal box and thread the ends of one rubber band through the holes in the inside bottom of the box.Pull the ends of the rubber band through the holes until the sinker is in the center of the box. Now, tie the ends of the rubber band together on the outside of the bottom of the box.
  7. Have someone help you by holding the bottom of the box. Now, thread the ends of the other rubber band through the lid of the box and replace the lid on the box. Make sure to pull the ends of the rubber band real tight so that the sinker does not touch the side of the box. Now, tie the ends of the rubber band together.
  8. Measure 1 m of masking tape and attach it to the floor. Place the box on its side on one end of the tape.
  9. Push the box gently so that it rolls along the tape.
  10. Observe the movement of the box. Mark how far the box rolls before it stops and starts to roll back towards you. Measure how far it rolled and record the data.
  11. Now, repeat steps 9 and 10, three more times. In each case, exert more force, pushing the box harder each time and recording your observations. You may want to take pictures of the results.
  12. Wash your hands thoroughly if you used a lead sinker.
  13. Analyze your data. What do you conclude? What happened when you pushed the box and when it rolled back/ Did the force of the push have any effect on the box`s potential and kinetic energy? Suppose you did not stop the box but just let the box roll on as it approached you, what do you think would have happened?
  14. Write up your project. Include the data chart and the photos. Make certain to include a bibliography.
  15. Jus t a suggestion for your exploration: Is there a toy that demonstrates what you have just investigated? Amazing what we can do with basic scientific principles!

Terms/Concepts: Energy;Potential energy; Kinetic energy; Conservation of energy


  • DiSpezio, Michael, Skoog, Gerald, Science Insights, Exploring Matter and Energy, Scott Foresman, Addison Wesley, 1999 p.47

Dr. Muriel Gerhard (Ed.D.) is a retired educator with fifty seven years of experience in all aspects of public education. She has been a teacher, principal, administrator, college professor, researcher, grants writer, change agent and science editor. She is the author of several books on education used as college texts. These include the best selling Effective Teaching Strategies with the Behavioral Outcomes Approach and The Behavioral Outcomes Handbook for Teachers and Administrators. Presently she is a consultant in science education and curriculum development, a marriage and family therapist, a newspaper columnist and an author. Her latest book, recently published, is a memoir of sixty vignettes entitled âNow That I`m Dead, I Decided to Write this Bookâ.