I’m running a 3d print for tomorrow’s project that’s going to take most of the day, so I wasn’t sure what we’d do for a project today. Then the boys and a few of their friends started playing with a slinky and I remembered a fun little experiment with a slinky.
What happens when you drop an uncoiled slinky from the ceiling?
here’s a closer look at the moment my son releases the slinky:
Here’s a second drop in which we zoom in on the bottom of the slinky:
Finally, here’s the 10x slo mo for that drop:
After the drops we talked about what was going on. I think this is a hard one for kids to understand, but they had some interesting ideas. To test some of those ideas we dropped an eraser from the ceiling at the same time that we dropped the slinky and saw which hit the ground first. Then we did the same thing dropping the eraser from the bottom of the slinky to see which one hit first.
Fun little morning of experiments!
Mike's Math Page 
Take the slow motion videos with your iPhone in slo-mo mode. It has a much better frame rate in slow motion. It’s smooth enough to compare how fast the top is moving immediately after the drop versus a solid object dropped at the same time. In other words, it helps show that the slinky is falling even though the bottom doesn’t move right away.
We did something similar, but not filmed. There were a bunch of kids over at the house when we were doing this (you can hear one of them in the first video). I don’t like filming with other kids since I don’t know how their parents will feel, so I the 2nd part was w/o camera. Anyway . . .
I held the slinky on the ceiling with one hand and one of our whiteboard erasers on the ceiling with the other. The question for the kids was which would hit the ground first.
Next I held the eraser at the bottom of the slinky and asked the same question.
Fun little project – though with ~6 kids and an average age of around 6th grade, the slinky doesn’t survive the project.