Physics Blogging Round-Up: Roman Engineering, Water, and Baseball

It's been a month since the last links dump of posts from Forbes, though, really, I took a couple of weeks off there, so it's been less than that in terms of active blogging time. But I've put up a bunch of stuff in July, so here are some links:

-- The Physics Of Ancient Roman Architecture: First of a couple posts inspired by our trip to Rome, this one looking at the basic mechanics of the key structural element of Roman building, the arch.

-- What Ancient Roman Buildings Teach Us About Science And Engineering: Second post about Roman construction, in which looking into the question of how they designed their major structures leads to thinking about the artificiality of the distinction between "science" and "engineering."

-- The Microscopic Physics Of Beautiful Fountains: Prompted by taking photos of a bunch of Roman fountains, a look at how microscopic forces create surface tension, which in turn makes most of the cool effects of splashing water.

-- Baseball Physics: Real Curves And Dead Balls: A brief sports interlude, prompted by a NIST video about baseball-related research by former director Lyman Briggs.

-- How To Stick Atoms And Molecules Together: A follow-on of sorts to the surface-tension-in-fountains post, looking at the origin of some of the microscopic forces that hold liquids together.

-- Pools And Beaches: The Fun Physics Of Water Waves: Rounding out the accidental water blogging theme, a look at the physics of water waves prompted by taking SteelyKid and The Pip first to Jones Beach and then to a wave pool at Six Flags Great Escape.

So, anyway, if you're looking for some uplifting physics content to buoy your spirits during the political conventions, here's a good reading list to start with.

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1) Minor nitpick about the physics/engineering points made about the Pantheon. Is it really the case that the "coffering" is, as you put it, mostly decorative? They are each little stepped arches, with the thicker part supporting the thinner part and transferring the load to the base. Strength while providing a signficant reduction in the weight that has to be supported, as you noted earlier. That said, the creative genius of the finest engineering is making an essential structural element appear decorative. Sometimes that is the work of architects, but it is often the work of someone who is "just" an engineer. The flying buttress is another pre-physics example.

2) The key to deception in baseball is that the brain learns to remove, as it were, the nearly parabolic motion of a ball experiencing normal drag forces in the air. That is what you learn when you play catch. The one that is easiest to analyze in intro physics is a changeup, delivered with an arm motion that is identical to a fastball but at a much lower speed. You can get them to work out the difference in vertical position (often as much as 8 inches) and time of arrival that gets a batter to take a strike that looks like a high fastball, and vice versa. Much cleaner than the messy business of the Magnus effect, which may be why they can be easier to hit.

By the way, I think the first video example with the basketball is an example of "knuckling". Slight changes in how the odd pattern at the ends of the ball meets the air flow must be responsible for the many sideways changes in direction of the ball.

By CCPhysicist (not verified) on 22 Jul 2016 #permalink

The "mostly decorative" line was based on some stuff in the paper and books I read about the Pantheon, where they showed that the coffering actually does very little to reduce the weight. and stress on the concrete. I think they said it was about a 5% reduction relative to a solid dome, but The Pip just started pitching a fit, so I can't look it up.

Thanks for that info!

They could not have calculated a 5% effect. Now I wonder if there are instances of earlier domes that were smooth and criticized as being boring by architectural critics.

By CCPhysicist (not verified) on 25 Jul 2016 #permalink