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walsh416

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Blog Entries posted by walsh416

  1. walsh416
    So we were touring an unnamed university's engineering department this weekend. It was pretty cool, the vibe was positive, the people were well adjusted and friendly, and all seemed well.

    Things took a turn for the dire as we stepped into the acoustics laboratory. Tragically, our tour guide uttered an utterly unforgivable sentence... "If I stood back to back with you inside this acoustically silent room and talked, you couldn't hear me because the sound-proofing is so great!"

    My first thought? "That's so cool!!"

    My second thought? "Wait... that's completely false, even in the most acoustically silent room around," and here's why....

    His premise for the statement was that the walls reflected no sound waves, and thus by standing directly behind someone you couldn't hear them speak. False. If you stand back to back with someone in the middle of a football field and say something, they will hear you immediately. There's nothing for sound waves to reflect off of (anything that might reflect them is far enough away that the time it takes sound to travel there and back would create a noticeable lag), yet one can still hear.

    So basically, no, nothing will reflect off of the walls, but sound will still travel throughout the room. This is because, unlike light, sound is not line-of-sight reception dependent. One vibrating air molecule will vibrate all those around it, not just the ones in the direction of projection, and so on.
  2. walsh416
    The earth is big and confusing, as is all the magma and magnetic and [insert another alliterative m-word here] magic that goes on inside it. To compensate for some of this magicky nature, the leap second was created.

    To back up a moment, there are many different time-standards in use today, all of them slightly different, and each of them quite confusing. Two of the most common are the atomic-clock based UTC, and the solar based GMT standard.

    As we have developed ever more accurate clocks, it's become clear that there aren't actually 24 hours (or 1440 minutes, or 86400 seconds) in each day. Though the difference is fractions of a millisecond, these inaccuracies snowball, and eventually the 'more accurate' UTC is no longer accurate and has strayed from GMT.

    To compensate for this straying due to variations in the earth's rate of rotation, the leap second was created. Used only when deemed necessary by observation, it has no set implementation (unlike, say, a leap year which comes every four years, except every 100 years, except every 400 years). And that's the cool part. We have no way of modelling when a leap second will be needed. There's no predictive formula or simple rule. In essence, we have no idea how to predict variations in the rate of rotation of our planet.

    And that's just freaking awesome.

    And slightly concerning.
  3. walsh416
    Ahh, sleep. Slumber. God's gift to mortals.

    Sleep is all about comfort. As many a mattress commercial has drilled into my head, not all mattresses are comfortable. There is a supposedly optimal point of squishiness and firmness and pillowness and sleepnumberness and weird-yoga-guy-meditating-on-a-mattress-for-no-apparent-reasonness. In short, different people like different mattresses.

    The generic want for a mattress, however, is relatively universal. This is due to the way gravity acts on the human body. Since we are not simply a point mass, gravity pulls on our entire body. When laying down, as if to sleep, this pulls us towards the ground. Due to the natural contours of the human body, the actual contact patch with a flat floor is relatively small, leading to high pressure areas (since pressure is inversely related to area, with a smaller area a greater pressure is produced). It is this pressure that is considered uncomfortable.

    A good mattress will conform to one's body, greatly increasing the size of the contact patch between human and bed. Speaking of beds and mattresses, hot damn one would be nice right about now...
  4. walsh416
    Lately, it seems as if everyone and their mother has a "Lifeproof" case for their iPhone. Seriously. If my mom had an iPhone she would absolutely buy one of these.

    The logic behind it seems to be that the average life is wet, rough, and crazy (enough said on that subject...) and that one should always use protection. For your phone. C'mon, people.

    But how do they work? Typically, they contain a series of seals made of a relatively malleable type of rubber. When compressed and then held in place by clasps or screws, the rubber conforms to the other surfaces, forming a watertight seal.

    For those of you looking to waterproof anything homebrew style (you know, waterproof a sink or a cat or a little sister just for fun), the trick is in the type of rubber, the surface it's conforming to, and the way it is held in place. The rubber must be flexible enough to meet up with the surface, but not so flexible as to deform and let water in. The surface has to be flat and straight, something it's easy to seal against. And finally, the rubber must be kept under essentially as much pressure as possible to maintain a seal.

    So that's it!! Post pictures of any waterproofed cats/sisters in the comments below!
  5. walsh416
    Well, Michael Scott would be proud. We have finally considered all our paper and copier needs and determined that lined, microperforated notebook paper is the key.

    Microperforation is the strip of tiny holes punched in notebook paper somewhere between an eighth and half an inch from the spine, selectively weakening the paper to tensile forces parallel to the spine. Essentially, it's designed to let you tear out a piece of notebook paper without ripping it or otherwise destroying it.

    By perforating the paper, there are fewer contact points along the intended direction of tearing. This means that for a given tensile force, each little paper piece (differential of paper length? not sure that's a thing...) feels greater 'pressure.'

    Microperforation is a game of compromises. Perforate the paper too frequently along the intended line of tearing and it will simply rip out when a force is applied. Perforate it not frequently enough and it will be as if it isn't perforated at all. Make the holes too big and now your paper looks stupid. Too small and they are ineffective.

    And all sorts of other thrilling compromises. Woohoo.

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