Physics with the Kids at 120 Frames a Second

I got a new camera for Christmas, not because there's anything wrong with my DSLR, but because I wanted something that could do high-speed video. So I now have a Casio point-and-shoot camera that will record up to 1000 frames per second, woo-hoo!

To break it in, I got the kids to help out by re-creating a classic slow-mo physics trick: the slinky drop:

Note that when SteelyKid lets it go, the bottom doesn't really move until after the entire length of the spring has relaxed. You can clearly see this in the still frame that's the "featured image" at the top of the post.

And since The Pip has to do exactly what his sister does, here's a similar clip with the slinky starting at a much lower altitude:

The camera doesn't record sound in slow-mo mode, so you can't hear him say "I did it!" immediately after the slinky hits the ground. Trust me, it's ridiculously cute.

And just as a bonus, here's a clip of SteelyKid running like a superhero (it takes about 10s before she gets into the frame):

These are shot at 120 fps, because that's a decent balance between fast enough to look cool (a quarter normal speed) and slow enough to not need a lot of extra light. The resolution gets worse at higher speeds, too-- at 1000 fps, it's just a narrow strip across the middle of the field. Still, the quality of the test videos is comparable to that of the high-speed camera we have in the department, which is about 20 years old and cost $30K. Technological progress is awesome.

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By Michael Norrish (not verified) on 03 Jan 2014 #permalink

Actually this does suggest a modification to the old free fall aparatus. If you go outdoors on a sunny day and take a picture of things falling you might be able to do as well as the old aparatus with the sparks on paper and the falling weight. The frames should provide a way to track the falling weight, and figure out the acceleration of gravity. (Might be a nice experiment in intro physics.