Supporting a Ball with a Stick

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What type of experiment is this?

Experimental procedure and explanation:

• This experiment is about supporting a styrofoam ball (use a hollow ball that is 10 cm in diameter) with a stick. A nozzle made from a PET bottle (to taper the flow and cause it to gush out forcefully) is attached to the dryer used in the experiment.
• Air is blown from the left downward diagonal direction, and the ball is placed on the stick and balanced.
• It appears as if the ball has been skillfully balanced. However, the fact is that even when the stick is removed, the ball continues to float in the air. The stick can be prepared as a prop and is merely for show.
• This experiment is based on the same principle as the “A Balloon that Floats at an Angle.” The flow of air from the dryer strikes the ball near the top, and then bends downward along the ball’s curved surface (Coanda effect). A diagonal downward force acts on the flow, and as a counteraction thereto, a diagonal upward force acts on the ball. Air resistance (the downstream direction of flow) and gravity (downward) also act on the ball, but these three forces are balanced and allow the ball to float in the air.
• The trick to this experiment is to select as lightweight a ball as possible and to make the air flow from the dryer tapered and strong.

[Keywords]	Coanda effect
[Related items]	Flow Around the Back of a Cylinder, A Balloon that Floats at an Angle, Drawn in Spoon
[Reference]	The Japan Society of Mechanical Engineers, “The Wonders of Flow (Nagare no Fushigi),” Kodansha Blue Backs, pp. 128-133. Ryozo Ishiwata, “Illustrated Fluid Dynamics Trivia (Zukai Zatsugaku Ryutai Rikigaku),” Natsume Publishing, pp. 214-215 and pp. 206-209.