  For the past decade, the SAIL labs at the University of Sydney have been
challenging students with short research projects that elucidate basic
principles of physics. These include the development of instruments launched on
cubesats, balloons, on telescopes or placed out in the field. This experiment
is inspired by the spectacular 2015 discovery of merging black holes with the
Laser Interferometric Gravitational-Wave Observatory (LIGO). Students are
profoundly inspired by LIGO, and for good reason, but it is challenging to
construct a table top demonstration of a gravitational wave observatory.
Instead we consider chirps which are remarkable transient phenomena in nature
involving both frequency and amplitude modulation, as we can demonstrate with a
spinning coin. In the case of the LIGO event, orbital energy is being released
as gravitational radiation; for the spinning coin, its spin/orbit energy is
being released dissipatively (sound, heat, air viscosity). Our experiment
involves a simple device to spin a coin remotely. This aids repeatability and
allows us to spin the coin within a vacuum chamber to examine the contribution
of air viscosity.
