18. What is the significance of a solid floating on its liquid? For example, why is it important that ice float on the water and not sink? Is there another scenario where a solid floats on the surface of its liquid?
Good question. A priori we would expect that the density of a solid phase would be greater than that of a liquid phase......
And yet the fact that ice floats on water shows that ice is LESS dense than liquid water. This is a highly unusual property in that most liquids are less dense than their solid phases. Offhand I cannot think of another liquid which is less dense in the solid phase. If someone is better informed than I on this matter, I would be glad to know the other exceptions.
And so icebergs float, and are a menace to shipping. But what if icebergs sank? What if when a berg calved from a glacier it sank to the bottom of the ocean? Quite possibly, the oceans would freeze from the bottom up, and the polar ice caps would persist over very large areas of ocean up from the southern and northern poles.