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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]

#51

Post by revscat »

ColinWright wrote: post #47
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

No worries, mate.

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

#52

Post by JTon »

hudibras wrote: post #36
paddyoloughlin wrote: post #25

I love how professionals who work at that facility and have probably deeply understood those principles for decades still display so much wonder at seeing this experiment with their own eyes.

I might be cynical, but I think they were putting on a show a bit. They already had some sort of apparatus set up to do the simultaneous drops. My guess is that it's a standard demonstration for visiting dignitaries and the like.

Perhaps their excitement no longer stems from the experiment itself, but from the reactions of the newcomers. Probably a terrible analogy, but sort of like witnessing a child's first experience hearing a musical instrument live. It can be energizing.

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

#53

Post by jacquesm »

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…

You can get rid of the air but you can't really get rid of gravity.

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

#54

Post by janzer »

4ad wrote: post #46
zwp wrote: post #40

Earlier quoted context omitted.

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, rat…

He's referring to the sequence starting at 4:15. Compare the close up real time shot that starts the later sequence to the slow motion at 2:52. The feather and ball leave the frame almost simultaneously in the earlier one but with ~25% of the feather still in frame in the latter.

After looking at it I agree with zwp, the editor really did make quite a mistake when assembling the last sequence.

[Edit: Screen grab of both http://imgur.com/EAKB5FK and I agree with the over all editing comment below. The slow motion shot as the first shot of falling in the vacuum was the thing that really stood out and I thought was bad on the first play through.]

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

#55

Post by 4ad »

janzer wrote: post #54
4ad wrote: post #46

Earlier quoted context omitted.

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, rat…

He's referring to the sequence starting at 4:15. Compare the close up real time shot that starts the later sequence to the slow motion at 2:52. The feather and ball leave the frame almost simultaneously in the earlier one but with ~25% of the feather still in frame in the latter. After looking at it I agree with zwp, the editor really did make quite a mistake when assembling the last sequence. [Edit: Screen grab of b…

Oh, I see what you mean now. Yes, definitely editing mistake :-). Apart from that, editing was bad altogether. There should have been many shots with the real-time fall. In fact, the first shot of the drop should have been in real-time.

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

#57

Post by antimagic »

aragot wrote: post #30
zelos wrote: post #21

Earlier quoted context omitted.

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.

I too though this "boyish wonder" face was phony. And yet the "boyish wonder" face will change the fate of the whole video when I show it to my 7yo. The rest is concrete and iron, not really appealing to kids, despite the potential awesomeness of the huge vacuum chamber.

What? No! I don't know about you, but I would have a silly grin on my face too if I actually got to see this experiment live - I mean it's such a classic result - we've all been told that this is what would happen, but very few of us actually get to see it. It's like the experience of seeing the moons of Jupiter the first time that you look at it through a telescope - yes, you know the moons are there, you've even seen photos of them in high-def colour, but there is something special about seeing it first hand.

So no, I don't think that that's a fake grin. But then, as with most female geeks, I have a huge Brian Cox crush, so I may be biased ;)

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

#58

Post by muglug »

zelos wrote: post #37
aragot wrote: post #30

Earlier quoted context omitted.

I too though this "boyish wonder" face was phony. And yet the "boyish wonder" face will change the fate of the whole video when I show it to my 7yo. The rest is concrete and iron, not really appealing to kids, despite the potential awesomeness of the huge vacuum chamber.

Indeed, but the show is on primetime BBC2, not CBBC or CBeebies. Ah, I guess anything that brings more viewers to science content is good. I just miss the old days of Horizon.

Me too. I grew up on Horizon, Tomorrow's World and QED.

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

#59

Post by gus_massa »

4ad wrote: post #46
zwp wrote: post #40

Earlier quoted context omitted.

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, rat…

There are two slow motion initial drops closeups:

* 2:52 -> http://youtu.be/E43-CfukEgs?t=2m52s

* 4:51 -> http://youtu.be/E43-CfukEgs?t=4m15s

The second one (4:51) looks like a drop in the air, because the barbules (the small parts of the feather) go "up" and flutter.

The first one (2:52) looks like an actual drop in vacuum. But I think that the oscillations are not related to the speed of sound in the feather, because I think that the sound travels too fast to be visible in this video. (I'd like to see some measured data.) I don't see waves traveling in the feather.

Initially the barbules hang down. After the feather is released, the feather is gravityless (in the non inertial reference frame) so the barbules go to their natural position, so they go "up", but only slightly and the flutter is minimal.

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

#60

Post by eevilspock »

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.

Do you not have kids or rarely interact/play with kids?

Kids are no, even though I know the relevant laws of physics and was intellectually not surprised, I was still in awe and it still violates my instinctive expectations. A visual equivalent to stepping onto a broken escalator.

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