Here, I describe physics experiments using the motions of an automatically controlled model train. To measure these train motions, a mobile ultrasonic sensor unit (provided by Mobile Physics Education Lab1) was used. This sensor unit can be connected to a smartphone (Android OS) for display using a USB cable, and is convenient to carry. These experiments have been effective in stimulating interest in mechanics classes by providing a fun way for students to learn about motion through observation of a model train. It has been previously shown that mechanics concepts can be taught with RealTime Physics (RTP) using an Arduino-controlled electric model train and a smartphone-based ultrasonic motion sensor. The challenge has been producing smooth accelerations of the train, but I’ve solved that here.

In RTP by Sokoloff and collaborators, students predict what graphs of a motion will look like, and then compare their predictions to...

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