1978 Activity: The Relationship Between Mass and Rotation Rate

To demonstrate that rotation rate depends on mass for a system with most of the mass in the middle, do the activity shown at right.  You will need a narrow plastic tube, string, and a few washers.  Tie one of the washers on one end of the string.  Thread the string through the tube and tie several washers on the other end (the mass).  Hold onto the tube and whirl the single washer around until it just balances the mass of washers below.  Try it with heaver and lighter masses by changing the number of washers below.  How does rotation rate depend on mass?