From Molecules to Gymnasts: How to rotate without angular momentum.
Holger Dullin
Dept. of Mathematics, Loughborough University
From classical mechanics we learn how to separate the vibrational and rotational
states of a molecule. Nevertheless pure vibration can lead to an arbitrary change
of orientation. In this talk I will explain this observation and discuss some of
our recent results for the CO_2 molecule [PRL 93:24302, 2004].
A similar mechanism allows a gymnast or diver to change orientation without angular
momentum. The shape of the human body in aerial motion is determined by the
Biomechanics Research Group at Loughborough University using 3D motion
tracking. I will describe simple models that explain how coupled rigid bodies
can rotate by changing their shape and discuss the relevance to the motion of
gymnasts and divers.