Atwood Machines: Close Looking and Design Thinking

The canonical device used in George Atwood's 1784 "A Treatise on the Rectilinear Motion and Rotation of Bodies" was the recent subject of Recreate Experiments from History, Elizabeth Cavicchi's seminar in the MIT Edgerton Center. There, I have been showcasing an 1870s Atwood machine from MIT's lecture demonstration collection. This coincided with a talk by Peter Heering, Professor of Physics and its Didactics at Europa-Universität Flensburg, on the reconstruction of a 1795 model at the Deutsche Museum - used to train elementary educators on leading Nature Of Science investigations. Additionally, we visited Harvard's Collection of Historical Scientific Instruments with its new director, Josh Gorman, to see a number of Atwood Machines including Harvard's English model purchased in 1799.

I'll share discoveries from close-looking at the design of these devices and broad themes that emerge from students as part of a pedagogy slowed down to focus on instrumentation. In particular, a number of elements reflect the device's original intent: to demonstrate proportionality in kinematic relations by synchronizing the sounds of release and collisions with metronome intervals - all through carefully pre-selected sets of weights. This is far from the idealized model in our intro courses of two masses and a (possibly massless) pulley being timed to measure g or simply being balanced at unequal heights to solidify force concepts - and which also hides the role of the designer and experimenter.