I was watching another boring webinar at work the other day. A boring person was making a boring analogy about how something is like icebergs, most of the real story is hidden beneath the surface. Oh, what a clever analogy! It almost woke me up from my boring-fact-induced slumber!
Anyhow — the cool part was that I started mentally doodling on icebergs and suddenly connected two facts.
* Icebergs are nine-tenths below the surface.
* Water is one of the only liquids that expands when frozen. This is why pipes break and houses and ships creak in winter, all the water turns to ice and takes up more room than before, stressing the structure. When it thaws there is room “left over” so more water and such can get in. This is also why driveways and roads crack over time.
I realized that the first one follows from the second. If ice is about 10% less dense than water then it will float in water. The denser water will force it up until about 10% of it is above the surface. At that point, the 10% of the iceberg that is out of the water will have enough weight to equalize the “missing” weight of the water under the surface from it’s lower density.
Cool! Can I confirm this by getting more precise numbers? Wikipedia says that ice is 8% less dense than water. Exactly how much of an iceberg is above water? Their iceberg entry gives more precise numbers. Dang, I forgot that icebergs form out of sea water… 1025/920 = +11%, close enough to “one-tenth” for me. And with a little more searching I can find the formulas and logic. Neato!
(And I left the webinar early.)