A circle or sphere moving radically around an axis (plate 9B) will describe a torus. If, for example, we think of torus-shaped toy-the hula-hoop (plate 9A), and a marble inside the hoop, in the course of a revolution around the hoop, the marble would travel the full interior space of the hoop based on the principles of ‘law of motion’.
A related principle is employed in the human body to provide a sense of balance (equilibrium). If you place sensors around the perimeter of the hula hoop that are triggered when touched by the marble, you will have a device that can sense the orientation of hula-hoop, since gravity will draw the marble to the lowest point in the hoop. If you place three such hoops at right angles to each other along imaginary ‘XY’, ‘XZ’ and ‘YZ’ planes (plate 10A), and you have a system that can detect almost any orientation. This is nearly identical to structures that evolved as our sensory organs for position, the semicircular canals located in the inner ear (plate 10B&C); the only significant differences are that the semicircular canals are not quite perfectly torus-shaped, and liquid, rather than marbles, triggers the sensors.
(Read more:http://en.wikipedia.org/wiki/Inner_ear ; Aug 3, 2012; http://www.hooping.org/tag/hula-hoop
-physics/ Aug. 19, 2012)
