A Balloon that Sticks to the Ceiling

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Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• Cut a styrene foam board (food tray, etc.) into a disc shape and cut a hole in the center. Install an attachment point for the balloon (a plastic bottle cap with a hole in it, or a small styrene foam cylinder with a hole). Plug this feature into a balloon. (In this experiment, a large 45-cm balloon is used.)
• Inflate the balloon and place it on a table. It will move in a sliding manner. A small gap forms between the table and the disc, where the air flows.
• At the periphery of the disc, the pressure of the flowing air is almost at the atmospheric level, but toward the center, the flow is larger, and the pressure will be less than atmospheric pressure (a larger kinetic energy means a smaller pressure). This will make the disc stick to the table.
• An air layer is formed between the disc and the table, causing a sliding motion.
• Applying the device to the bottom of the table will have similar effect, and the disc will stick to the table. (You will have to make components as light as possible.)
• “Bernoulli’s theorem” (Law of energy conservation for fluids) explains that in one continuous flow, the pressure is lower where the flow is faster (more kinetic energy) compared with that where the flow is slower (less kinetic energy).

[Keywords]	Bernoulli’s theorem
[Related items]	A Trapped Ball
[Reference]	“The Wonders of Flow” Japan Society of Mechanical Engineering, Kodansha Blue Backs pp. 102-107