The Whirling Table was purchased by Dr. Barnard to demonstrate properties of centrifugal force, especially as they relate to motions of planets. On one end of the whirling table, turning upon a wooden frame, are two balls of unequal weight connected by a brass rod. A notch on the connecting rod marks the center of gravity between the two balls. If the center of gravity is aligned over the center of the whirling frame, the smaller ball will rotate around the larger as the handle is turned. Equilibrium sustains the position. This demonstration illustrates that a smaller body can revolve around a larger body if they share a common center of gravity. We can apply this principle to the solar system. The earth moves around the sun, sharing a common center of gravity which, through complex calculations, can be determined to be within the body of the sun.
What happens if the center of gravity is not aligned with the center of motion? If the notch marking the center of gravity between the balls is moved away in either direction from the center of the whirling frame, the balls will fly to the end of the frame, without a common center of gravity, whirling objects would fly out and away. The center of gravity within the body of the sun acts as one way of preventing the planets in our solar system from flying uncontrollably out in space.
On the opposite end of the whirling table is an upright rod supporting two thin brass hoops. When still, the shape is a sphere. If the handle is turned, however, the hoops spin. The bands of the hoop fly outward because of centrifugal force, and the hoop slides down the rod, assuming an oval shape called an "oblate spheroid". In a similar manner as the earth spins, it assumes the shape of an oblate spheroid, its poles flattened and its equator bulging slightly.
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