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The hammer-feather drop in the world’s biggest vacuum chamber [video]

thekidshouldseethis.com

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Re: The hammer-feather drop in the world’s biggest vacuum chamber [video]

#41

Post by oneeyedpigeon »

sambeau wrote: post #38
oneeyedpigeon wrote: post #29

Earlier quoted context omitted.

I find it interesting that Brian Cox, the presenter and avowed scientist, obviously finds it so 'surprising' as well. Maybe that's the true meaning of being a scientist, though - he doesn't truly believe it until observing it with his own eyes.

>Brian Cox, the presenter and avowed scientist, I think you mean "Brian Cox: Professor of High-energy Particle Physics, member of the High Energy Physics group at the University of Manchester, and the ATLAS experiment at the Large Hadron Collider at CERN (who also presents popular science programmes in the UK)" I think his career as a scientist deserves a little more recognition than "avowed". And, as for his career…

Sorry; I have every respect for Brian Cox, unlike others on this thread. I think I'm merely using totally the wrong word.

Re: The hammer-feather drop in the world’s biggest vacuum chamber [video]

#42

Post by scottlocklin »

zelos wrote: post #21
paddyoloughlin wrote: post #17

I wish the producers were less enamoured of their slow-mo and showed us the whole thing in real-time. The "weird" thing is seeing feathers plummet to the ground and I wish we got to see more of that.

This is a Brian Cox show we're talking about, not a science show. I'm surprised there weren't more slow mo shots of Cox doing his "boyish wonder" face.

Glad to know I'm not the only one who finds Cox incredibly annoying. FWIIW, the exploratorium in SF and the Boston Science Museum both have experiments of this nature. It is a cool vacuum chamber though. Reading some of the NASA early docs on building such things can be quite fun.

Re: The hammer-feather drop in the world’s biggest vacuum chamber [video]

#43

Post by noselasd »

baldfat wrote: post #19
frozenport wrote: post #15

Earlier quoted context omitted.

From another perspective, these technologies left us with little science of utility (Tang?) while developing intercontinental ballistic missiles that loom over humanity like the Sword of Damocles. When historians from far off planets visit our nuclear wasteland they will see our thinly veiled space program as the beginning of end. :-)

Quick list of more inventions that are not Tang http://en.wikipedia.org/wiki/NASA_spin-off_technologies

Even something as mundane as error correction coding were developed at NASA, for communicating with spacecraft - technology that's now present in e.g. CD/DVDs, and every mobile communication system.

Now, if they hadn't developed it, someone else probably would, but perhaps not at that time - leaving us at years behind where we currently are with e.g. the speeds on our mobile devices.

Re: The hammer-feather drop in the world’s biggest vacuum chamber [video]

#46

Post by 4ad »

zwp wrote: post #40
nmeofthestate wrote: post #31

Earlier quoted context omitted.

And for the violently impatient, the actual drop: http://youtu.be/E43-CfukEgs?t=2m52s

Fortunately you beat me to it. I was going to post the later sequence at: https://www.youtube.com/watch?v=E43-CfukEgs&feature=youtu.be... But on closer viewing that is a disastrous montage: the first few seconds (before cut away) show the feathers fluttering and the bowling ball starting to accelerate away; the slow-motion segue is under vacuum conditions though. The film editor's intention is that the two shots appe…

What do you mean? The close-up shot at 2:52s is under vacuum. The "fluttering" you see is the elastic wave in the feather caused by the sudden drop in internal tension. The feather is an elastic object (to a first approximation). When the feather is hung, there's internal tension keeping it stationary and giving its shape. When the feather is unhooked, this internal tension doesn't just disappear instantaneously, rather an elastic wave travels through the feather at the speed of sound in the feather. Because the feather is not a perfect elastic medium, the effect you see is a damped harmonic oscillator, but it takes non-zero finite time to dampen sufficiently.

This is true for the big ball too, except that the speed of sound is orders of magnitude faster in it, and the spring constant of the material (steel?) is also many order of magnitude larger than the spring constant of the feather.

The center of mass of both objects falls at the same rate. At t=0, d^2x/dt^2=0 for the points closer to the ground and d^2x/dt^2=2g for the points that were just unhooked. Also see https://www.youtube.com/watch?v=mAA613hqqZ0

Re: The hammer-feather drop in the world’s biggest vacuum chamber [video]

#47

Post by ColinWright »

revscat wrote: post #44

Commander David Scott did this same experiment as part of Apollo 15 in August of 1971, in an even larger vacuum: https://www.youtube.com/watch?v=KDp1tiUsZw8

That's one reason why I posted the link to this site, rather than directly to the YouTube video, as explained here:

https://news.ycombinator.com/item?id=8556363

The text of the site I submitted has kindly been posted by DanBC[0] here:

https://news.ycombinator.com/item?id=8556409

[0] https://news.ycombinator.com/user?id=DanBC

Re: The hammer-feather drop in the world’s biggest vacuum chamber [video]

#48

Post by danielweber »

paddyoloughlin wrote: post #17

I wish the producers were less enamoured of their slow-mo and showed us the whole thing in real-time. The "weird" thing is seeing feathers plummet to the ground and I wish we got to see more of that.

With the HTML5 player you can double the speed; it's entirely in browser, so you can probably capture the Javascript event and make it go at 5x or 10x or whatever is needed to play at full speed. (It'll be up to you to then dub in Yakety Sax.)

Re: The hammer-feather drop in the world’s biggest vacuum chamber [video]

#49

Post by t__r »

dia80 wrote: post #2

I know how this will turn out but my intuition is screaming otherwise.

I find it a bit easier to understand if I imagine similar size and shape objects with a different weight. Say, a bunch of balls with equal radius but different weights. Does a near-zero-weight ball fall with a near-zero speed? Of course not. Etcetera.

Re: The hammer-feather drop in the world’s biggest vacuum chamber [video]

#50

Post by vixen99 »

teach wrote: post #7
bjackman wrote: post #3

I guess this is a pretty superficial complaint, but this is a 2nd-generation clickbait-site link (posted on io9, reposted on thekidsshouldseethis.com). Why not post the Youtube link directly? This isn't really Hacker News material, anyway.

Especially since the linked site is starting to hit resource limits. I had to refresh a few times before it would load. Here's the youtube link: https://www.youtube.com/watch?v=E43-CfukEgs

A version without Cox would definitely pile on the views. As it is I will forgo the pleasure.
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