They don't fall where intended.

Let's take a look!

What type of experiment is this?

Experimental procedure and explanation:

• We submerge the marbles into the water.
• The object is dropped from directly above the intended target. However, it sways and does not fall on the target.
• When an object moves, it usually creates an irregular vortex behind it. This is called a separation vortex, which causes the object to sway due to the lateral force acting on it.
• The knuckleball in baseball or the " No-Spin Shot " in soccer are known as magic balls due to the same principle, and they change in unpredictable ways that even the players themselves cannot predict.
• This experimental video was produced with the support of JSPS Grant-in-Aid for Scientific Research 18K03956.

[Keywords]	Separation vortex
[Related items]	No-Spin Shot, Sinking a Japanese Penny Underwater
[Reference]	Ryozo Ishiwata, "The Wonder of Flow," Kodansha Blue Backs, P174-179. Ryozo Ishiwata, "Illustrated Fluid Dynamics Trivia", Natsume Publishing, P96-97 and P198-199.

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