Water that Won't Overflow

Let's take a look!

Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• Cut a horizontal slit in the side of a plastic bottle and seal it with vinyl tape.
• Fill this bottle with water and screw on the cap. When you remove the vinyl tape, barely any water emerges. This behavior is similar to “Plastic Bottle with Holes.”
• Open the slit and put a disposable chopstick through to expose the water surface. The water inside still will not flow out.
• The exposed water surface is at atmospheric pressure.
• The reason the water will not spill out is because the pressure in the upper part of the bottle is lower than atmospheric pressure (which is the water pressure of the exposed water surface), as given by “water density × gravitational acceleration × height.” The pressures are in equilibrium at this condition, and so the water will not spill out.

[Keywords]	depth and pressure
[Reference]	“Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natsume Publishing, pp. 18-19 and p. 52
[Warning]	Take extra caution to not hurt yourself when cutting a slit in the plastic bottle.