Surely you've seen this game before, although you may not know how it was invented.

In 1943, Richard T. James was trying to develop a means for suspending sensitive shipboard instruments aboard naval vessels. While working with the torsion springs, he accidentally dropped one. Seeing how the spring kept moving, he came up with the idea of a toy.
Thus, The Slinky spring was born . According to U.S. Patent 2415012 of 1947, it could move up to 100 steps per minute. What is the frequency of your Slinky when walking down the stairs?