Conservation of Energy Rocks

Somehow, when I am teaching Physics, I feel like I am holding out on my students until we get to work and energy. Once we start problem solving using energy rather than dynamics, there is a certain elegance, and a much greater portability – principles of energy are quite general, and can be applied outside the Physics classroom much more readily than, say, Newton’s Laws. Central to using W&E are the law of conservation of energy and the Work-Energy theorem. In order to illustrate the law of conservation of energy in class today we took a video of a pendulum and dropped it into Tracker. Here is the result:

I love the way this came out, showing the kinetic and potential energies swapping back and forth. This was a very easy, and very visual demonstration.

5 thoughts on “Conservation of Energy Rocks

    1. ed Post author

      The ol’ bouncing ball is good too – adds efficiency to the picture, and a discussion of how the ball behaves as a spring.

  1. Dan Fullerton

    Hi Ed! Pleased to meet another physics blogger! I’ve added a link to your blog on, and saw that you were looking for a discussion forum to add to your site. If you’d like, you’re more than welcome to use the forums at — I can easily tailor categories and permissions for you and your students if you’re so inclined.

    Best Wishes,

    1. ed Post author

      Thanks – I added Physics in Flux to the blogroll. And I’ll add a “contact me” somewhere 🙂

  2. Shawn Cornally

    Welcome to the fold! Your blog is being passed around twitter, so I’d be expecting some attention from the WCYDWT folks!

    I love the post. I’ve played around with teaching energy conservation first, and it has worked really well. I teach mgh and .5mv^2 right away, and then we fill in the details as we move through other unites. The kids seem to get a much better handle on the abstractions of work and energy this way, but I haven’t done any solid research.

    Thanks for the post!


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