Oscillations of a candle burning at both ends

Abstract

A candle burning at both ends will oscillate vertically about the horizontal, forming the popular "candle see-saw" or "stearic motor." The reason for these oscillations is that at any particular instant, more drops of liquid wax drip from the lower end than from the higher one. As a result, the lower side becomes lighter and moves upward, while the other side becomes heavier and moves downward, becoming the lower one. Thus the center of gravity oscillates continuously from one side to the other. We present a quantitative model describing these oscillations and verify it experimentally. © 2009 American Association of Physics Teachers.