Book: # 5

INTRODUCTION:
The Skylab orbital workshop provided a unique opportunity to investigate various properties of materials.  In this unique weightless environment the usual vibratory modes can be much different.

What does a Wilberforce pendulum have in common with water?  Perhaps, because you have not been an astronaut in a weightless environment, you have never noticed the similarities.  In Skylab, where water drops are only constrained by the surface tension of water, the oscillations of water drops bring to mind the oscillations of a pendulum.

During the 171 days that astronauts lived in the weightless environment of Skylab the demonstrated both the oscillation properties of water and of a Wilberforce pendulum.  This film shows some of these possible modes of oscillations.

FILM SYNOPSIS:
Scene 1:  The film opens showing two hands holding a Wilberforce pendulum.  One end of the pendulum is released and the resulting oscillation of the pendulum in a weightless environment is shown.

Scene 2:  Water drops placed on the ends of the aluminum rods, 0.95 cm (3/8") in diameter and about 3 cm apart are shown.  One drop, colored red, is oscillated.

Scene 3:  The Wilberforce pendulum, stuck to a wall, is shown oscillating with one free end. 

Scene 4:  A hemisphere of water, about 8 cm in diameter is shown held to a surface by adhesion.   The hemisphere of water is excited by a stroke from a drinking straw.  Its oscillations are shown.

Scene 5:  Longitudinal vibrations of the Wilberforce pendulum are demonstrated.

Scene 6:  A water bridge between the two aluminum rods is shown and oscillations of the bridge are produced. 

Scene 7:  The complicated, two ends free, oscillations of the Wilberforce pendulum are shown.

Scene 8:  With two glass rods a water drop, suspended on a string, is excited to oscillate.

Scene 9:  The Wilberforce pendulum is twisted and released to show its complex rotational and transitional oscillations.