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Water dome

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What type of experiment is this?

Experimental procedure and explanation:

  • Applying water to the plastic bottle cap creates a dome of water.
  • The water hitting the cap spreads along the top surface of the cap and flows out radially in the same direction. This is due to the effect of inertia.
  • Meanwhile, the surface tension acting on the water attempts to reduce the surface area of the membrane, so when the flow rate is reduced, the dome is squeezed downward and approaches a spherical shape. If the flow rate is high, the inertia becomes strong and the dome becomes large. If the flow rate is low, the surface tension becomes strong and the dome becomes small.
  • Water is an important resource. Be careful not to waste water.
[Keywords] Inertia, surface tension
[Related items] Make a film of water
[Reference] “The Wonders of Flow,” Japan Society of Mechanical Engineering, Kodansha Blue Backs, P15, P62-67
“Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natsume Publishing, P208-209, P48-49

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Last Update:3.3.2017