Jump with Buoyancy 2

Let's take a look!

Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• By testing with plastic bottles of different shapes, you can infer that the resistance to flow (drag) decreases as the rear section tapers more gradually. In other words, gradually tapered rear sections lead to smaller vortex separations and less drag.
• In this experiment, the height of the jump is affected by not only fluid resistance but also the magnitude of buoyancy. The last bottle had a sharply tapered rear section and a large volume (buoyancy is proportional to volume). Therefore, it jumped very high.
• This experiment can be conducted in a bath tub. Try it with various objects.

[Keywords]	resistance (fluid dynamic drag), separation
[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