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Drops to Droplet Mechanics
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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Update: June 2012
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