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  • So this is the modeling that I've been doing.

  • And I thought this was done with purpose off trying to explain the data that was extracted from one of the movies of real fooling Slinky.

  • What you see in this one is that the terms of the top are snapping together behind a front that propagates down.

  • So the blues section of the top is the part that has collapsed so initially nothing's collapsed.

  • And then Maura Maura, the Slinky is is collapsed as that front runs down the slinky.

  • And how close is that to what actually happens?

  • Well, I think that if you watch the movies, you can say that the turns down collapse instantly.

  • So how did you improve on that model?

  • Well, I assume that there's essentially a fixed number of turns over which that collapse occurs behind the front.

  • Those turns.

  • They're not collapsing in on hammering together at the top.

  • You can actually relaxing, and in fact, I've colored blue, the section that is under collapse or has collapsed, and that's that's far more obvious if you look at the other video.

  • But this to me looks much more realistic, much from any more true to.

  • That's why I did it.

  • So if someone asked you why When you let go of this link, it is the bottom, not fall.

  • What do you say?

  • I'd say that there is.

  • You know what you're doing.

  • You're changing something at the top.

  • And then there's a finite time for that information about the change to get to the bottom of the Slinky.

  • I mean, that happens even with a rigid bar with steel bars.

  • Just the time is very, very short.

  • But a lot of people on the Internet get uncomfortable with the term information.

  • I mean, what are we saying by information is a signals.

  • It's a signal.

  • So it's something you know, whenever you do something physically to have to effect a change causalities, you do something and there's, ah, cause and effect on.

  • That's between the two.

  • Information has to propagate.

  • The signal has to propagate if they're not at the same location physically the same, like so how long does it take for the compression wave to get from the top to bottom?

  • About 1/3 of a second it collapsed.

  • Time is there.

  • Is there any way to extend that time because, you know, if you decrease the the spring constant, make it a softer Sprinkle.

  • Yes, then that takes longer to collapse, which is sort of make sense the way propagates more.

  • So you make it.

  • If you increase the master, this slinky gets longer.

  • Maura nursery that collects processing away that.

  • Yeah, you need any kind of a heavy slinky that is very loose.

  • It So it isn't it what, you reckon like a lead slinky or I, If you have extended systems than to consider the motion of the center of mass and extended system, you need to consider the external force that acts on the center yet on the center of Mass.

  • And that's gravity and that stops interacting.

  • You know instantly that this is released was there to begin with, but it's suspended, it's held out.

  • And then once you take away that suspension, that that center of mass has to start accelerating downwards instantly.

  • So if you watch the movie, say that the red dot Indeed, it's a good test with modeling.

  • The red dot does start to accelerate, and you didn't build that into the model.

  • You know, we allowed that to after the fact, I calculate that you know what you got the model of each time step.

  • Calculate where that center of Massey's and it doesn't stop the full immediately.

  • I think way We're talking about this earlier, and you actually see the bottom of this thing start to rotate now.

  • So there's some kind of torture, all modes.

  • I'm twisting mode Macy Signal that gets down to the bottom of the slinky.

  • First, Russia's ahead, but it doesn't actually relax.

  • It doesn't release any tension.

  • Clearly does the bottom just stays.

  • Anyone knows that allows other turns coming down, that the tension is relaxed.

  • I think this one's gonna need.

  • So in this one, you don't let go of the top of the Slinky, but you hold the slinky collapsed to the top and you release the bottom and you hold it.

  • You keep the top fixed.

  • And so what it does is it also lays back and forth.

  • That's a basic mode in which that whole thing and also light and, of course, that mo just depends in a simple way on the parameters of sling keys of the period of isolation, that motor good test for the parameters that we got out of the other modeling out of falling for things like this is a very basic mode.

  • That's what I think.

  • This is a kind of breathing mode.

  • This is in and out.

  • Every turn moved in a very simple way in and out breathing or fundamental motive oscillation you really wars.

So this is the modeling that I've been doing.

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落下するスリンキーは重力に逆らう? (Does a Falling Slinky Defy Gravity?)

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    林宜悉 に公開 2021 年 01 月 14 日
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