To illustrate the dynamics of a SLINKY suspended from one end and released.
A SLINKY is suspended from one end and released from rest. Q: What will happen when the SLINKY is released: (a) The bottom end will begin to accelerate upward as the entire SLINKY collapses, (b) The bottom end will begin to accelerate downward as the entire SLINKY collapses, or (c) The bottom end will remain instantaneously at rest as the SLINKY collapses? A: The bottom end will remain at rest until the entire SLINKY has collapsed, at which time it will begin to accelerate downward.
W. J. Cunningham, The Physics of the Tumbling Spring, AJP 15, 348-352 (1947). J. G. Fox and J. Mahanty, The Effective Mass of an Oscillating Spring, AJP 38, 98-100 (1970). S. Y. Mak, The static effectiveness mass of a slinky, AJP 55, 994-997 (1987). Jeanne Marie Laskas, The Lady behind the SLINKY, Reader's Digest, November 1993. M. G. Calkin, Motion of a falling spring, AJP 61, 261-264 (1993). Richard A. Young, Longitudinal standing waves on a vertically suspended slinky, AJP 61, 353-360 (1993). A. P. French, The Suspended Slinky - A Problem in Static Equilibrium, TPT 32, 244-245 (1994).