So which is it? The result may surprise you.
First, make your bets on what you think will happen.
A Slinky is a loose tension spring. If you let the whole thing uncoil and hang down, the tension is enough to hold up the bottom against the pull of gravity.
Because the Slinky is dropped from the top, Cross explained in his study, it takes time for the motion wave to travel down the spiral and "communicate" to the bottom part that the top part fell — and that the tension is no longer there.