On the Poggendorff experiment

Poggendorff showed experimentally, in the middle of the 19th century, that the weight of an Atwood machine is reduced when it is brought to motion. His experiment has been revisited from time to time, making use of instrumentation that reflects the technological development of the moment. In this paper, the evolution of the experiment is briefly overviewed and a modern version of it, using a widespread commercial measurement system, is presented. The relevance of the ideas underlying the Poggendorff experiment for undergraduate physics teaching is also pointed out.