Science: Kinetic and Potential Energy

I thought I’d take some time to write about one of our recent science lessons using Building Foundations of Scientific Understanding, or BFSU. This is going to be long so I’ll post it in two sections.

In a previous lesson we discussed energy and its basic forms of motion, light, heat, and electricity. We have also covered gravity and to a lesser extent friction. This week we were to expand on that topic in lesson C-3 Concepts of Energy II: Kinetic and Potential Energy.

I started the boys off with some videos of roller coasters from the Discovery channel series Build It Bigger. Then we moved on to two videos the boys have seen before from a series they ask for often: Eureka! EJ at 7, probably understands physics as well as I do just because of this 30 video series. Highly recommended.

While they watched I set up the activity room with some demonstrations to help illustrate kinetic and potential energy. We had a pendulum hung from the ceiling, some rubber bands, balloons, 4 large steel ball bearings, and of course a marble coaster. They played for about 15 minutes before we sat down to discuss each item.

First we defined our terms:

  • Kinetic Energy: The energy of movement.
  • Potential Energy: Energy that is available to be used as kinetic energy.

One of our objectives was for the kids to understand that an object’s potential energy depends on whether it has the right position and condition for energy to be present. Discussing the Eureka! episode on potential energy I asked the boys if the rock on top of the cliff had any energy. They understood that it did have energy because it was in a position where gravity could act on it causing it to fall and make work. Yay! As an aside, because they understood that so easily, I asked them to consider how the rock got up to the cliff in the first place. That was a bit trickier which is just as well because it leads to our next objective!

Next we had to learn that an object does not have energy unless energy has been put into it. As we played with the marble coaster we identified that a stationary marble on the floor has no potential energy due to its position in relation to the vertical pull of gravity.  I slowly moved the marble from the floor to the top of the coaster asking questions about what I was doing in terms of energy. EJ was able to state that I was using some of MY energy, transferring it to the marble. We discussed this with each demonstration until it became clear that energy must be put into something before we can get energy out of it. Then we discussed the coaster in terms of kinetic energy. As the marble rests at the top of the coaster it has potential energy and once it begins to travel down the coaster it has kinetic energy. We also discussed why the marble eventually stops and related this to what we know of space where there is no friction and low gravity.

Next we focused on the concept that ENERGY INPUT = ENERGY OUTPUT. As I held up the weight at the end of the pendulum I asked whether we could predict how high up it would swing to the other side when I let go. Would it go higher, the same height, or lower? JD though it would go higher while EJ said it would swing to the same height. EJ had the right idea, he felt it would go the same height because of the amount of energy that was transferred into the weight by my lifting it. He forgot however, that there is another force acting on the weight, namely friction.

Before breaking for lunch we listened to a silly little song called, what else? Kinetic and Potential Energy! Then they played with two online illustrations of energy in roller coasters. Eduplace’s Energy and Motion simulation, and Fetch! With Ruff Ruffman’s Whoaler Coaster! game (another absolute favorite in this house).

Stay tuned for part II coming soon!

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5 responses to “Science: Kinetic and Potential Energy

  1. will you teach my kids about science? 🙂

  2. Hehe. We do science with another family and that’s FOUR kids! It works well… usually.

    • Farrar, you are awesome, must be the teacher in you. I think it would be rather like herding cats for these four. But two are not even quite 5 yet so I suppose there’s still hope 🙂

  3. excellent write up and informative videos, ive just finished my kinetic energy paper but ill update with some of this information.

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