The falling chain of Hopkins, Tait, Steele and Cayley

A uniform, flexible and frictionless chain falling link by link from a heap by the edge of a table falls with an acceleration g /3 if the motion is nonconservative, but g /2 if the motion is conservative, g being the acceleration due to gravity. Unable to construct such a falling chain, we use instead higher-dimensional versions of it. A home camcorder is used to measure the fall of a three-dimensional version called an xyz -slider. After frictional effects are corrected for, its vertical falling acceleration is found to be a x / g = 0.328 ± 0.004. This result agrees with the theoretical value of a x / g = 1/3 for an ideal energy-conserving xyz -slider.