Remove a rod from the tube

Let's take a look!

What type of experiment is this?

Experimental procedure and explanation:

• Let's remove the stick from the tube with the wind from a hair dryer. Two 22-cm-long polystyrene rods were prepared. The tube diameter (inner diameter) is 6.3 cm, and the depth is 50 cm.
• First of all, the rod on the right side can be taken out by blowing air along the wall. This rod is octagonal and has a gap between it and the tube. When the wind is blown into this gap, the rod will rise. This principle is the same as "Removing a Ball from a Cylinder".
• Next, the same wind that was blown on the left rod does not work. Therefore, when making a tornado-like vortex, the rod floated upward. This principle is the same as "Remove a ball from a deep location 2".
• However, the rod could not be pulled out. This rod is a cylinder with a small gap between it and the tube. Therefore, it was difficult to send air into the gap, like the rod on the right, and it did not rise unless a vortex was created. Ultimately, the rod could not even be taken out.
• The rod on the right side can also be taken out by making a vortex in the same way as on the left side.

[Keywords]	Momentum theory, vortex, pressure
[Related items]	Removing a Ball from a Cylinder, Remove a ball from a deep location 2
[Reference]	“Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natsume Publishing, P200-201

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