Archive for June, 2013

Mo' Slower, Mo' Better

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Self-siphoning beads is more mesmerizing in slow-motion

Siphoning Beads

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The “cornering ability” of the beads seems to depend on the tension. Makes for an interesting effect.

Monkey Evolution

How not to shoot a monkey: video analysis of a classic physics problem.

Interesting progression of the shoot-the-monkey problem.

I was also amused to note that the blowgun version of the problem, which I’ve done, is one of the iterations of this as it has become more “sanitized” in textbooks.

Conic Scones

Play with your food: How to Make Sconic Sections

In what follows, we’ll show you how to bake cone-shaped scones, to slice them into plane geometric curves, and to highlight those curves by selective application of toppings. We’ll also discuss some of the methods that didn’t work so well, as we refined our methods for making these.

Don't Believe the Financial News

This Mysterious Ancient Egyptian Statue Has Started Moving On Its Own

“I noticed one day that it had turned around,” museum curator Campbell Price told the Manchester Evening News. “I thought it was strange because it is in a case and I am the only one who has a key.

“I put it back, but then the next day it had moved again,” Price said. “We set up a time-lapse video and, although the naked eye can’t see it, you can clearly see it rotate.”

Yes, you can see it rotate — during the time that people are walking past it, and not at night, when the place is empty. It’s settling from the vibrations it experiences.

Protip: pay attention to the actual scientists’ explanations, and not the wacky notion that the statue is trying to show off its backside. Also, if you offer the possibility that it’s magnetic, you should know that the idea is easily tested.

I Have Figured Out Your Evil Plan

As part of the money saving in the sequester, DoD facilities have been told their thermostats will be raised a high as 80ºF (26.7ºC). We’ve avoided going that high thus far, because we’re going to do some mitigation like installing window tinting to reduce the overall heat load (plus there’s the leverage of operational equipment that can’t be allowed to overheat, but I don’t know if that card is being played and we humans are peripheral beneficiaries)

The rumor is that the chill water in the heat exchanger is going to be set at a much higher temperature than before, at around 14ºC, which is slightly below the typical dewpoint for the summer air. This saves money because condensing water out of the air takes a lot of energy. Warm, wet air (27ºC, ~50% relative humidity) will have upwards of 11 grams of water per kg of air, and air at a comfortable 22ºC and 30% RH has but 5 grams. The heat of vaporization is around 2.5 kJ/gram of water, while for air the specific heat is around 1 kJ/kg-ºC, so cooling from 27ºC down to 22 removes about a third of the energy as compared to condensing 6g of water, so if you can basically eliminate the water removal by only cooling to the dewpoint, you will save quite a bit of money. (They aren’t completely avoiding the removal of water, but the new system scales it back by quite a bit). For the recirculated air, they are just removing whatever we add from our evaporating perspiration and spilled coffee.

Unfortunately, 1 kg of completely saturated air at 14ºC still has 10 grams of water in it, and that represents 60% RH at 22ºC, which is really sticky. I’ll bet the mold will love it, though.

Spoiler Alert

Does the Dog Die?

Do you turn off Old Yeller before the end so you can pretend that he lived a long and happy life? Did a cute pet on a movie poster make you think it would be a fun comedy but it turned out to be a pet-with-a-terminal-illness tearjerker instead? Are you unable to enjoy the human body count in a horror movie because you’re wondering whether the dog’s going to kick the bucket? Have you ever Googled “Does the [dog/cat/horse/Klingon targ] die in [movie title]?”

I imagine this is useful if you are trying to avoid tears and wailing in young ‘uns.

Funny thing is that there are movies where concern for an animal’s well-being is far from the main focus, and might be considered a little strange, like The Godfather. Or there’s Indiana Jones and the Last Crusade, which has a happy face because Indiana the dog is OK, but acknowledges that rats are torched and birds collide with a plane.

Death to Monkeys!

MIT video (embedding is disabled) doing the famous “monkey drop”experiment — a monkey in a tree drops when a shot is fired. Because the bullet and the monkey both accelerate at g, you should aim straight at the monkey. I remember doing this in the basement of my neighbor’s house, with a blow-gun and a solenoid dropping a metal target.

This is Not Leading, So Get Out of the Way

Mandating Scientific Discovery Never Works

The history of science is replete with unexpected discoveries with profoundly important effects. The World Wide Web was not developed to address a public need but to help physicists communicate at a high-energy physics laboratory engaged in esoteric studies of the fundamental structure of matter. Theoretical studies of the nature of light emitted by hot objects ended up leading to the development of quantum mechanics, which describes the weird behavior of electrons in atoms. In the process, it led to the development of transistors and all the modern electronics on which modern computers and our information economy is based.

IOW, what works best is letting scientists investigate the area(s) of interest to them. Enough of what they find will be useful to us all, somehow.

It's No "Alan Parsons Project"

Physics Buzz and Uncertain Principles take on the plausibility of a purported x-ray death beam that was recently in the news.

Fermi Problem Friday: X-Ray Assassins

On “Death Rays”

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