The purpose of this letter is to present an improved version of the centrifugal effect demonstration device that I had reported in this journal.1 The earlier version was six inches in diameter and contained water and a small air bubble. The improved version is 10 inches and contains three immiscible fluids—approximately equal volumes of dyed glycerin with green food color and (clear) mineral oil, and a large volume of air. However, construction method and device set up remain the same.
The top view of the device resting on its turntable base is shown in the left image. At rest the fluids are layered due to gravity, with glycerin (heaviest) at the bottom, mineral oil in the middle, and air (lightest) at the top. When the device is spun by hand fast enough, the resulting radial pressure, which increases with radius, causes the fluids to redistribute or separate. This is...