Time is always a factor in class, especially if you teach AP courses. To set up and run a good lab assignment takes a while. The more we work with Vernier Dynamics Cart and Track System with Go Direct^{®} Sensor Carts, the more we appreciate them. They are real time savers. For example, the law of conservation of mechanical energy lab (one of the versions). The setup takes 2-3 minutes per group. Students experiment with the conversion of potential gravitational energy to kinetic energy. From my experience, usually, students understand well that kinetic energy is zero at the starting point and potential gravitational energy is zero on the floor (if we make it a zero level). More troubles they have for intermediate moments of time. I always do a lot of problems that involve these intermediate points, including graphs of kinetic and potential energies. But some students have problems with it anyway. I believe that the described lab can help to eliminate some of these difficulties.

The simplest setup that includes a cart, track, super pulley, and weight on a string. If you run it once, you get graphs of position and velocity.

Now you can analyze as many points as you want. Calculate kinetic energy, potential gravitational energy, work of gravity etc. Changing masses of the cart and/or the weight on the string, you can get as much material for the analysis as you want. I asked my students to analyze just one graph because it was only the first part of the lab, the second was on the spring potential energy. But the results were really good. Graphical Analysis 4 allows you to modify graphs to present different calculated values. Below are the examples:

- Potential energy

2. Kinetic energy

3. And the best of all – both on the same graph (I added also total mechanical energy)

Due to a really low friction total energy is almost horizontal. For many years I have given to my students a problem that required to draw these graphs. Now we can on the fly get these graphs from the lab experiment.

All these experiments you can run with non-wireless Vernier equipment but I was never successful with motion detectors, and the process of setup always have taken a lot of time. With new equipment, it takes just 2-3 minutes.

Disclaimer: I have never worked for Vernier nor got any payments from them 🙂 I just appreciate their new products.