Tuesday, October 31, 2017

Trick or treat? See for yourself

It's been a little quiet around here for a variety of reasons. So let's shake off some dust for ... Halloween? Why not?

Four drops of food coloring are added to the center of a half-filled "skinny fish tank" (a.k.a., Arbor Scientific Laser Viewing Tank) resting on a low-friction turntable (Pasco's Rotating Chair platform).

The tank is then given a spin. And, well..?

It made me say those magic words all people in science prize: "That's funny!" I didn't know what to expect, so in some ways, this wasn't overwhelmingly surprising. Still though...



I get the parabolic surface. But what's going on in the dye? I'm sure there's a lovely, simple explanation that I should know. But I don't.

If you do, kindly leave it in a comment. I am your student.

1 comment:

John Millard said...

My first thought is it has something to do with the initial bobbing up and down of the parabolic curve (most easily seen at the beginning of the spin). Maybe that bobbing creates waves on the surface that reflect off the edges of the tank and form a small (too small to see) standing wave along the surface of the water. The antinodes of that standing wave are agitating the water vertically thereby "pulling" the dye vertically, giving rise to the regular "peaks" of dye along the tank?

Just hazarding a guess! Intriguing!