Counting To Ten

July 24, 2012 By: erik Category: Funny, Offspring, Videos

Counting to Ten (thumbnail)We have been making slow, but steady, progress on Nora’s counting abilities. She can more or less get up to about fifteen in both languages, and she’s begun to make statements like “There are three cookies on the table” as well. The other day I thought I’d record a video of her counting to mark her progress, and she did very well, despite manifesting her most common errors.
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Friday the 13th is most common 13th

January 13, 2012 By: erik Category: Fighting Stupidity, Geeky, Math, Musings

Friday the 13th Facts and TheoriesI’ve always been fascinated by superstition, and friggatriskaidekaphobia – or, to be more clear, paraskevidekatriaphobia – strikes me as a particularly interesting one. The origin can only be traced back into the 19th century. I am disappointed to discover that experts find little reason to associate it with the slaughter of the Knights Templar on October 13, 1307, exactly seven hundred years before my wedding day. Oh well, something else Dan Brown got wrong. As if to show just how arbitrary the choice of Friday is, the Spanish speaking world fears Tuesday the 13th, and they even have their own tongue-twisting phobia word: trezidavomartiofobia.
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How big is the Earth’s shadow on the Moon?

December 16, 2011 By: erik Category: Geeky, Math, Musings, Photos, Science

Earth's UmbraWhen I saw yesterday’s Astronomy Picture of the Day, I was fascinated by just how big the Earth’s shadow is on the Moon. When I made a comment to this effect on Facebook, my friend, Josh Grady, said, “It’d depend on the distance between the two, no?” Of course the size of a shadow depends on the distance to the object its cast upon, but I hadn’t considered that the distance from the Earth to the Moon varies, due to its slightly elliptical orbit around the Earth-Moon barycenter, by 42,840 km, causing it to appear 12% smaller at its apogee than at its perigee. This raised the question: What are the minimum and maximum sizes of the Earth’s shadow on the Moon?

To the geometrymobile!
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How fast do you need to drive in the rain to keep your rear window dry?

November 09, 2011 By: erik Category: Geeky, Math

Car Sketch - Rear Window AngleLast week, we had quite the deluge, which coincided, unfortunately, with me having to drive 120 km. I noticed that whenever I slowed down, the rear window would get wet and hard to see out of. Once I sped up again, one wiper pass dried it off and it stayed dry until I slowed down again. This is an obvious scenario for anyone who has ever driven, or anyone who thinks briefly about the physics involved: when you’re driving fast, the rain doesn’t hit your rear window. Out of the blue (or gray, in this case), my mouth spoke the words, “I wonder what’s the minimum speed I have to drive to keep the back window dry?” My wife immediately intuited that “it depends on the shape of the car”, by which she meant the angle of the rear window. This insight made the original question all the more interesting to me, because it gave me an equation to plot! Are you getting excited yet?
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