Wednesday, July 16, 2014

Why do Heavy Ships Float?



Armchair Science is a Kindle ebook available at Amazon. It contains over 120 short mysteries of science that can be solved from a single observational clue, without the need for experimentation.




Science is not a collection of facts. Science is what facts teach us; what we can learn about our universe, and ourselves, by deductive thinking. From observations of the night sky, made without the aid of telescopes, we can deduce that the universe is expanding, that the universe is not infinitely old, and why black holes exist. Without resorting to experimentation or mathematical analysis, we can deduce that gravity is a curvature in space-time, that the particles that compose light have no mass, that there is a theoretical limit to the number of different elements in the universe, and that the earth is billions of years old. Likewise, simple observations on animals tell us much about the migration of continents, the evolutionary relationships among classes of animals, why the nuclei of cells contain our genetic material, why certain animals are long-lived, why the gestation period of humans is 9 months, and why some diseases are rare and other diseases are common. In “Armchair Science”, the reader is confronted with 129 scientific mysteries, in cosmology, particle physics, chemistry, biology, and medicine. Beginning with simple observations, step-by-step analyses guide the reader toward solutions that are sometimes startling, and always entertaining. “Armchair Science” is written for general readers who are curious about science, and who want to sharpen their deductive skills.

Here is an excerpt from the book:

Clue 21. An object can displace a volume of water that has a weight equal to or less than its own weight; but no more than that.

Deduction. Objects made of materials that are denser than water can float, if they are shaped properly.



Illustration. A cruise ship. How does it manage to float so high above the water line? Source: Wikipedia, and donated to the public domain by its author.

Resolution. As an object begins to sink into water, it will displace water until it gets to the point where the displaced quantity of water matches its own weight. After that, the object must stop sinking (i.e., must stop displacing water). As you lower an enormous ship into the water, regardless of the material from which it is constructed, the object will displace water (i.e., sink) until it has displaced a weight of water that is equal to its own weight; at which point, it ceases to sink. If the object is designed so that the weight of water it displaces (i.e., its own weight) is reached prior to the point when the object disappears beneath water's crest, it will float.

Because objects cannot displace a weight of water exceeding their own weight, enormous ships, built from materials that are denser than water, will float. Caution is advised: if you knock a hole into the wall of a floating ship, water will enter, increasing the weight of the ship, and thus increasing the amount of water the ship can displace before it must stop sinking. The ship will continue to sink as more and more water enters its hull.

I urge you to read more about this book. There's a good "look inside" of the book at the Amazon store.

- Jules J. Berman, Ph.D., M.D.

tags: deductive science, science mysteries, deductive reasoning, ebook, general science reading, general science book, science puzzles, scientific amusements