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Name: Edward Q.
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 2001-2002


Question:
I have noticed that when water drops hit certain surfaces like stainless steel and porcelain,they sometimes burst into tiny balls of water that spread out from the origin of the drop.I have looked in many books and asked all the people I can think of, why this happens, but no one knows.


Replies:
Edward,

It is similar to why a falling vase shatters into pieces flying in all directions. The sudden force on the water drop is greater than the force holding molecules together. The drop "breaks". There is no movement to the north, south, east or west before the collision, so there is no preferred direction for the droplets to fly. As a result, they go in all directions (conservation of horizontal momentum). The drop only flies apart if moving fast. A slow drop will vibrate and spread out a little, but will stay in one piece.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College


Ed,

When the cohesive (water molecule-to-water molecule attraction) forces of the water exceed the adhesive (molecule-to-surface) forces, the water will better "stick" to itself than to wet the surface. Thus, the scattering little balls of water.

Regards,
ProfHoff 403



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