Measuring g using a rotating liquid mirror: enhancing laboratory learning

摘要

We describe a low-cost yet experimentally challenging method to measure the acceleration of gravity, g, using a liquid in a rotating bowl and a laser pointer. The idea underpinning this novel method is that the rotating liquid surface will form a parabolic reflector which will focus light into a unique focal point. By measuring the height of the focal point, g could be determined to 9.78±0.13 m s~(?2). We discuss the pedagogical merits of this method compared to more traditional methods for measuring g, and how it can be implemented as an experimental problem at different educational levels.