1. 2009
    Oct
    15

    Lifting a car with duct tape

    It’s Mythbusters day again, and this time Adam and Jamie are testing the strength of duct tape in some rather interesting ways. Like using it to lift up a car, for example. This is a pretty cool demo, but there’s one thing that irked me: on the show, there was quite a bit of speculation along the lines of “Can duct tape really hold up a car?” Yes, in fact, duct tape can hold up anything, if you use enough of it. As they suggested in the show, when you’re using strips of tape (or string etc.) to hold up an object, the total force required is split among all the different strips of tape, and if your strips are approximately evenly distributed (in some particular sense), the force is approximately evenly split. With 100 strips of duct tape lifting a 5000 pound car, that’s an average of about 50 pounds per strip, which is reasonably within the limit that Adam and Jamie found (albeit somewhat unscientifically) — even accounting for the fact that some strips are carrying more weight than others.

  2. 2009
    Oct
    10

    Bullet Fired vs. Bullet Dropped

    With their season premiere this week, the Mythbusters are testing a classic physics story, so of course I had to comment on it. The myth in question is that if you fire a bullet from a gun held horizontally, it will hit the ground at the exact same time as a bullet dropped without any horizontal motion at all.

    Of course, in the mind of any physicist, this is no myth at all — the laws of physics that tell us this should happen are so well established that they’re almost beyond question. Specifically, it’s the linear independence of orthogonal vectors, which means that components of motion that are perpendicular to each other, like gravity (vertical) and constant velocity (horizontal), don’t get in each other’s way. You can split the motion of the bullet into two perpendicular components and analyze each one separately. This is, in fact, one of the first things students learn in an introductory physics class: analyzing the motion of a fallen or thrown object. The equations \(x = v_{0x}t\) and \(y = -\frac{1}{2}gt^2\) work for both the fallen bullet and the dropped bullet, just with \(v_{0x} = 0\) in …

  3. 2009
    Oct
    08

    LHC to test hyperdrive

    Wait, what?

    Just stumbled across this nifty little idea: that a particle moving at high speed can actually repel a stationary object in the other direction. I haven’t read the paper but if the summary is to be believed, this is very cool. Although it’s not actually faster-than-light propulsion, so not quite the hyperdrive of science fiction.

  4. 2009
    Sep
    07

    TV browser

    Way back when I was first looking for a program to display TV schedule listings, I tried TV-Browser and decided against it because the listings are arranged in a big grid so that you have to scroll sideways pretty far to see what’s on the various channels. But now, I decided to take a closer look at it and I’m thinking that the other features of the program may be enough to make up for that. Up until today, I’ve mostly been using Maxemum TV Guide, which, while being perfectly adequate, is rather bland. The user interface is pretty basic, which is not a bad thing in and of itself, but it gives the impression that not a lot of work was put into the design. This is clearly not the case with TV-Browser. There’s a lot of information, a lot of options, and the grid organization is more intuitive than Maxemum TV Guide’s simple list. Plus, it looks like you can define channel groups to limit the amount of data shown at any one time, which kind of reduces my major complaint. So it looks like I’m switching to TV-Browser.

  5. 2009
    Aug
    29

    Utah: our role model??

    This is interesting: Utah has passed a law imposing stiff penalties for typing text messages while driving.

    This is more interesting: apparently that is a big deal. Because according to the article, all other states (except Alaska, sort of), have practically no penalty at all. Typing while driving is generally treated as an accidental cause of a crash, in the same league falling asleep at the wheel or (I presume) losing control of the car, because supposedly people don’t know that it’s a risky activity.

    Wait, WTF?

    Okay, first of all, when did being stupid become an excuse? For potentially killing people? Real accidents, like falling asleep at the wheel, are out of people’s control (well, to some extent), but typing is absolutely not. You had to consciously make the choice to pull out your phone and take your attention away from the road to push those keys. I fail to comprehend how anyone could think this would be a good idea.

    And besides: how is it that we need to take our regulatory cues from Utah? Seriously, get it together, states.

  6. 2009
    Aug
    28

    Failure of the equivalence principle?

    Here’s an interesting physics tidbit, to close out a long break from the science on this site: a couple of scientists claim to have proposed an experiment which theoretically should be able to distinguish between gravitational and inertial accelerations. This would break one of the most widely accepted laws of physics, the equivalence principle of gravitational and inertial masses — in other words, the belief that the \(m\) in \(F=ma\) is the same as the one in \(F=-GMm/r^2\) is now being challenged.

    But I’m not really buying it. The equivalence principle is one of those things that just makes sense, that’s why it’s been accepted so widely for so long. If it’s going to be overthrown, I need to see hard evidence, and nobody’s even done this experiment yet. I’m not familiar with the calculations they did that predict different responses for gravity and kinetic acceleration, but it’s easy to imagine that they might have missed a term somewhere, or perhaps one of the equations they used is incomplete, or whatever, and that would make physics a lot more consistent (albeit a lot less exciting) than the alternative of …

  7. 2009
    Aug
    21

    Survey wtf?

    How’s this for a survey question:

    Please indicate the degree to which you agree or disagree with each of the following statements on a scale from (1) strongly disagree ro (9) strongly agree.

     

    I have a pet.

    1 - Strongly Disagree23456789 - Strongly Agree

    Do I strongly not have a pet, or only halfheartedly not have a pet? Does that mean I halfheartedly do have a pet?

    I’m putting 5. Schrödinger’s cat.

  8. 2009
    Aug
    10

    Why I am a nerd

    Observe, if you will, the following incident that took place between me and one of my friends at a wedding reception this weekend:

    He shows me a text message he’s sending,

    Actually, I == teh drunk.

    Wedding reception

    Me: “I see you didn’t forget the double equals”

    Him: “Yeah, all my text messages compile properly”

    Me: “Although, I guess in this case using a single equals would be a quick shortcut to getting drunk…”

    Him: [rofl] “How are you not an alcoholic with a mind like that?”