Stairs? Where this Slinky is going, we won't need stairs.
The science junkies at Veritasium decided to drop a Slinky and capture its descent on high-speed video, and the result is impossibly cool. Regardless of the height from which it's dropped, the bottom of a fully-extended Slinky will appear to hover motionless as the top plays spring-loaded catch-up. Check out the toy's remarkable levitation act:
So how does it work? Mike Wheatland, associate professor of physics at the University of Sydney, explains that it has to do with two forces at work on the bottom end of the Slinky: the force of gravity pulling it down, and the force of the coiled spring pulling it upwards. Effectively, those two forces cancel each other out, so the bottom appears motionless. There's much more science behind it, but it all boils down to hovering Slinky.
Which is nearly as impressive as a Slinky on a treadmill. A wonderful toy, indeed.