A Plastic Bottle that Draws up Water

Let's take a look!

What type of experiment is this?

Experimental procedure and explanation:

• The plastic bottle and the water in the cup are connected by a vinyl hose.
• The end of the vinyl hose inside the plastic bottle is positioned higher than the water level in the cup. Try using this vinyl hose to suck water from the cup.
• Lift the cup once to release the air inside the vinyl hose. When you lower the cup back to its original position, you will see that water has been drawn up through the hose to a level higher than the water level in the cup. Why does this happen?
• There is a hole at the bottom of the plastic bottle, allowing the water inside to connect with the water outside in the tank. When you lift the plastic bottle, the water level inside the bottle becomes higher than the water level in the tank. As a result, the air pressure at the water surface inside the bottle, which is at a higher position, becomes lower than atmospheric pressure (this is called negative pressure). If the difference in water level is h₁, then the pressure difference can be calculated as shown in the experiment “A Balloon that Inflates when Lifted”:
  (Pressure difference) = (Density of water) × (Gravitational acceleration) × h₁.
• Similarly, if the difference in height between the outlet of the vinyl hose and the water level in the cup is h₂, then the pressure difference there is
  (Pressure difference) = (Density of water) × (Gravitational acceleration) × h₂.
• If you lift the plastic bottle and the cup so that h1 becomes larger, making h₁> h₂, the air pressure inside the plastic bottle will be lower than the pressure at the outlet of the vinyl hose. As a result, water will be sucked up from the cup through the hose.
• This video was produced with the support of the JSPS Grant-in-Aid for Scientific Research (18K03956).

[Keywords]	Depth and pressure, negative pressure
[Related items]	A Balloon that Inflates when Lifted, Water Fountain 3 (Using Negative Pressure)
[References]	Ryozo Ishiwata and Mitsumasa Nemoto, “The Wonder of Flow,” Kodansha Blue Backs, pp. 38–41. Ryozo Ishiwata, “Illustrated Fluid Dynamics Trivia,” Natsume Publishing, pp. 18–19.

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