Slinky Drop Extended

All right, you've made your prediction, and we've tied a tennis ball to the base of the Slinky. Here, and now we're going to extend it and drop it, and see what happens to the tennis ball. The heavy weight of the tennis ball is going to stretch the spring a little bit further, so I'm going to cheat a little bit by shortening it a fraction at the top. All right, so we can see both the top and bottom ends.

Sounds good? On the count of three, I'll drop it. Ready? One, two, three! Whoa! What did you see there? It fell very rapidly. I need to look at that inflamation to see what's going on. All right, let's go to the slow motion [Music] footage.

So when you watch that, you see that the tennis ball really remains stationary until the whole Slinky is collapsed above it, correct? The, uh, white force acting on the tennis ball is countered by the tension force acting upwards until the information travels down the Slinky that the tension has changed.

It's really quite strange because it's as though the falling Slinky can support the tennis ball in a way. That's what it looks like, and indeed, that's what it's doing. I just find that so amazing and so counterintuitive.

We study physics because lots of unexpected things happen, and it's those unexpected things that make physics interesting. It's, uh, it's really strange. It's like, uh, if you were falling out of a plane and you had a big enough Slinky, you might, uh, be okay for a little while. I wouldn't try it, though; you're better off with a parachute.

Exactly! All right, well, thanks Rod, much appreciated your, uh, your help today. It's been fun.