We've all seen the videos where someone holds a slinky, hanging at full extension, by the top, and drops it, right? The bottom will just hang there, suspended in midair, while the top falls, until the top catches up with it.
The explanation is that the spring tension on the bottom of the slinky is pulling upward with the same force as gravity is pulling down, counteracting it, until the top falls down and releases this tension. And that makes sense, kind of, but the thing I wonder is, why does the tension have to be released first?
If gravity acts on every point equally, (technically it doesn't, if you want to get really pedantic it's pulling on the bottom every-so-slightly more than on the top, but that's not really relevant,) doesn't it seem like a reasonable outcome that, once it's unsupported, the whole thing would fall, still under tension, and then collapse from the bottom up and release the tension once it hits the ground, rather than hanging in the air and collapse from the top down?
