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He grew up in Bethesda, Md., and while he was still in high school, he did his first published work on the strength of metals that had been made porous. He was a semifinalist for the Westinghouse Science Prize (the forerunner of the Regeneron Science Search) and won several other awards.

That work helped him get into M.I.T., which he entered as a pre-med student planning to get an M.D./Ph.D.

He was soon led astray.

Dr. Hu’s undergraduate adviser at M.I.T. was Lakshminarayanan Mahadevan, a mathematician who works to describe real life processes in rigorous mathematical terms.

Dr. Mahadevan, known to students and colleagues as Maha, investigated wrinkling, for example. Naturally he won an Ig Nobel for that work.

“Maha lit the fire,” Dr. Hu said. Before he encountered his adviser’s research, he said, “It didn’t really make sense that you could make a living just playing with things.”

But he came to see the possibilities.

He stayed at M.I.T. for graduate work, in the lab of his adviser, John Bush, a geophysicist. Dr. Bush remembers him as very enthusiastic.

Asked by email about some of Dr. Hu’s wilder forays into the physics of everyday life, he said, “A sense of playfulness is certainly a good thing in science, especially for reaching a broader audience.” But, he said, “targeting silly problems is not a good strategy, and I know that David has taken considerable flack for it.”

Dr. Hu may be the first third-generation (in terms of scientific pedigree) Ig Nobel winner, because Dr. Mahadevan studied under the late Joseph Keller, a mathematician at Stanford University. Dr. Keller won two Ig Nobels. One was for studying why ponytails swing from side-to-side, rather than up and down, when the ponytail owner is jogging. The other was an examination of why teapots dribble.

After M.I.T., Dr. Hu did research at the Courant Institute at New York University, another hotbed of real-world mathematics. He moved to Georgia Tech, after Jeannette Yen, a biologist there, told the university they ought to take a look at him.

Dr. Hu’s research may seem like pure fun, but much of it is built on the idea that how animals move and function can provide inspiration for engineers designing human-made objects or systems.

The title of Dr. Hu’s book refers to the “robots of the future,” and he emphasizes the way animal motion offers insights that can be applied to engineering — Bio-inspired design.

When Brazil’s Pantanal wetlands flood, for instance, fire ants form rafts so tightly interlaced that water doesn’t penetrate their mass. When he picked up such a mass in the lab, Dr. Hu writes, it felt like a pile of salad greens.

“The raft was springy, and if I squeezed it down to a fraction of its height, it recoiled back to its original shape. If I pulled it apart, it stretched like cheese on a pizza.”

He found out that the ants were constantly moving even though the shape of the mass stayed more or less the same. They were breaking and making connections all the time, and they became, in essence, a “self-healing” material.

The idea is appealing for many engineering applications, including concrete that mends itself and robots that self-assemble into large, complex structures. Depending on the force applied to them, a mass of a hundred thousand ants or so can form a ball or a tower, or flow like a liquid.

He and students in his lab also showed that the reason mosquitoes don’t get bombed out of the air by water droplets in a rainstorm is that they are so light that the air disturbed by a falling drop of water blows the mosquitoes aside. The finding could have applications for tiny drones.

They also showed that the ideal length for a row of mammalian eyelashes is one-third the width of an eyeball. That gives just the right windbreak to keep blowing air from drying out the surface of the eye. Artificial membranes could use some kind of artificial eyelashes.

And what about urination? It didn’t make sense to Dr. Hu that a grown man and an infant would have roughly the same urination time.

After he sent out undergraduates, under the guidance of Patricia Yang, a graduate student, to time urination in all the animals at the Atlanta Zoo, the situation became even more puzzling. Most mammals took between 10 and 30 seconds, with an average of 21 seconds. (Small animals do things differently.)

The key was the urethra, essentially a pipe out of the bladder, that enhanced the effect of gravity. Even a small amount of fluid in a narrow pipe can develop high pressure, with astonishing effects.

Water poured through a narrow pipe into a large wooden barrel can split the barrel. Dr. Hu said the experiment, known as Pascal’s barrel, can be replicated nowadays with Tupperware.

What is interesting about the urethra biologically is that its proportions, length to diameter, stay roughly the same no matter the size of the animal (as long as it weighs more than about six and a half pounds).

The 21-second average urination time must be evolutionarily important. Perhaps any longer would attract predators? But then predators are subject to the same rule. In any case, the principle of how to effectively drain a container of fluid could be useful, Dr. Hu wrote in the original studies, to designers of “water towers, water backpacks and storage containers.”

As usual, in his book Dr. Hu does not neglect the human side of his work, or treat it too seriously. He refers to the urethra as a pee-pee pipe. And he corrects his son when he brags that only he, not his sister, has a pee-pee pipe.

Not so, Dr. Hu insists. The urethra is present in males and females.

Once older, his children may never forgive him for this book. But middle school science teachers and nerds everywhere will thank him.