Large drop towers let you experience a couple of seconds of nearly free fall before stopping gracefully in magnetic brakes or bouncing a number of times on compressed air, as in the Turbo Drop tower considered in this work, where many complementary representations are used. An accelerometer taken along on the ride captured the forces experienced by the body, and a pressure sensor provided a simultaneous proxy measurement of elevation. These data can be treated numerically: integration of the accelerometer data gives a velocity graph which can be compared to derivatives of the elevation data obtained from the pressure sensor. Plotting elevation versus velocity gives a phase portrait for the damped oscillations of the gondola before it comes to a stop. These abstract mathematical and graphical representations are complemented by screen shots from a video as well as from a virtual reality movie offering the view from the point of a rider. Forces and acceleration overlaid in a 2D version of the VR movie give a geometric illustration of Newton's second law, in addition to the mathematical treatment. This work thus provides a wide range of representations, aimed to support student representational fluency and conceptual understanding of important force and motion concepts.
|Status||Published - 2020|