Jump with Buoyancy 1

Let's take a look!

Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• Submerge each object completely under water and release it. The objects rise and jump out of the water. The lesser the water resistance, the higher they jump.
• Water resistance is highly dependent on whether a vortex forms behind the object as it rises, that is, whether separation takes place.
• When a vortex forms behind an object, a large resistance to flow is generated, and the object will not jump very high.
• When you point the sharp end of a cone toward the bottom, the vortex is small, and the resistance will be small. Therefore, it will jump high.
• To reduce resistance, it is important to taper the backside.
• An object with small water resistance also has less air resistance. The resistance to fluid flow is called “drag.”

[Keywords]	drag (fluid dynamic drag), separation, buoyancy
[Reference]	“Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natsume Publishing, pp. 62-63 and 68- 69 “The Wonders of Flow,” Japan Society of Mechanical Engineering, Koudansha Blue Backs, pp. 136-139