Recent content by Bill Foster

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    Xmgrace: making one double plot out of two single plots

    Grace plots are typically stored in files with a *.agr extension. Suppose I have two (or more) single plots: plot0.agr plot1.agr ... Suppose I want to combine these plots into a single file, with each plot displayed side-by-side, or a smaller plot within a larger, or whatever. We can call...
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    What is this? Recognize it? Used for?

    You all haven't identified this contraption yet?
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    Discover Ne^9 Energy Levels Using NIST Database - Missing Values?

    Using the NIST database, I get the following energy levels for Ne^9. But there some some values missing (where the ? is shown). Any of you know these numbers, or where I can find them? Thanks. 1s2 1S 0 0.00000 1s2s 3S 1 7299940.0 1s2p 3P° 1 7379327.8 1s2s 1S 0 7382680.0...
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    What is this? Recognize it? Used for?

    I don't see how a beaker would attach to those arms anyway.
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    What is this? Recognize it? Used for?

    The upper arm is immobile. The chain attaches to something which leads into the box. I imagine that when the chain is pulled, it pulls that lower arm up, against spring loaded tension from inside the box. Whatever it's meant to hold, it cannot be too heavy, or the whole thing will tip over...
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    What is this? Recognize it? Used for?

    I'll bet some 80 year old high school science teacher knows what it is.
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    What is this? Recognize it? Used for?

    I'm skeptical. The notches on the arms of the C clamp look like they're meant for something like string. The arms looks like they're meant for holding something under tension. There's probably a spring inside the box providing the tension. The chain releases the tension. The chain...
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    What is this? Recognize it? Used for?

    Ah, of course. It all makes sense now. thanks.
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    What is this? Recognize it? Used for?

    I won't dispute your claim. But...HOW? And for what kinds of injuries?
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    What is this? Recognize it? Used for?

    http://www.stevenferris.com/whatisit.jpg Anybody here recognize this? Does it have a name? What's it used for? Thanks.
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    Lorentz transform on the Dirac equation

    The energy solutions to the Dirac equation are E=\pm\sqrt{p^2+m^2} So I apply a Lorentz transform to that. But first, I need to expand it, right...
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    Artificial Gravity: Benefits & Uses

    Combining the two equations I listed previously... \vec{F}=m\vec{a}=m\frac{v^2}{r}\hat{r} There is your basic equation for centrifugal force. Now, assume the station is rotating at some angular velocity \omega rad/sec. You'll need to convert that into a velocity: v_s=\omega r...
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    Artificial Gravity: Benefits & Uses

    You'll need to know how fast the station is rotating. If it's not given, then you'll have to write the answer in terms of \omega.
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    Artificial Gravity: Benefits & Uses

    \vec{F}=m\vec{a} \vec{a}=\frac{v^2}{r}\hat{r}
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    Lorentz transform on the Dirac equation

    Since the energy solution contains a square root of the momentum (and the Lorentz transform acts on the momentum), I need to expand the function first before applying the Lorentz transform?
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