Re: Another pondian difference

In message <5$fItWQ++HIJFwqR@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Mike Barnes <mikebarnes@xxxxxxxxxxxxxx> writes
In alt.usage.english, J. J. Lodder wrote:
No floating object is ever -on- the surface, strictly speaking.

I'd say that the floating object locally depresses the surface, and
remains on it.


From memory, the Water Boatman insect is something actually walks ON the water, on the surface tension layer. It is not wetted by the water, but you can see that it does depress the surface.

However, most things do dip well into the water. According to Archimedes' Principle, "the up-thrust on any body which is fully or partially submerged in a fluid a force equal to the weight of the fluid displaced." [I'm not sure if this law applies to water boatmen, but it probably does.] If the weight of the liquid displaced is insufficient, the body sinks.

Wetting is the contact between a liquid and a solid surface, resulting from intermolecular interactions when the two are brought together. Some things resist this interaction, but a wetting agent can be added to the liquid in order to break down the effects of surface tension, and allow the intimate contact which is necessary for wetting to occur.

Well, that's my 2c worth.
--
Ian
.

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