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Data analysis and experiments - John C. Kirk

Oct. 15th, 2006

05:12 pm - Data analysis and experiments

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From:totherme
Date:October 16th, 2006 12:27 pm (UTC)
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Good stuff - can't see the original discussion, but I'm all in favour of trying to be rational :)

A few new data points:

I think if you dropped a box full of feathers, and a box full of ball bearings, the latter would fall faster, because it's denser. In a vacuum, they'd fall at the same rate, but in atmosphere one of them's presenting more surface area per mass than the other, so there's a difference. I think the experiment you were looking for was a lead ball bearing vs a lead cannonball - if they're the same shape and the same density, they should fall at the same speed. If this seems weird to you, think of a balloon filled with helium vs a balloon filled with air :)

As for the Oprah thing, the BBC did a fairly good experiment in 2002 called Trading Races. They're not quite scientifically rigorous, but they seemed to have a genuinely thoughtful investigative air about them. If you google for that programme now, you'll find a couple of feedback pages, which I think are fairly interesting.

More recently, it seems there's been a more serious american version of the experiment taking place over the summer.
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From:johnckirk
Date:October 16th, 2006 04:18 pm (UTC)
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I think if you dropped a box full of feathers, and a box full of ball bearings, the latter would fall faster, because it's denser. In a vacuum, they'd fall at the same rate, but in atmosphere one of them's presenting more surface area per mass than the other, so there's a difference. I think the experiment you were looking for was a lead ball bearing vs a lead cannonball - if they're the same shape and the same density, they should fall at the same speed.

Hmm, I may be displaying my ignorance of physics here - hopefully someone else can chime in on this. I'd expect a lead ball bearing and a lead cannonball to fall at the same speed, on the basis that I'd expect 1000 lead ball bearings to all fall at the same speed, so it shouldn't matter if they're glued together. If objects were falling in a vacuum, then I'd expect the pillowcase and paperweight to fall at the same speed, since air resistance would be irrelevant; I've heard about an experiment from one of the moon landings that tested this, using a feather and a hammer.

More recently, it seems there's been a more serious american version of the experiment taking place over the summer.

It's interesting that you mention that, because I was reading a conspiracy theory about that recently - it appears that at least two of the family members have IMDB pages listing their prior acting experience, so there's some doubt about whether they were being told to behave in a particular way.
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From:johnckirk
Date:October 16th, 2006 04:50 pm (UTC)
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Ok, following up on this I did a Google search for Galileo "same size" "different mass", and found this discussion. The basic gist seems to be that he did try the experiment of dropping two balls off the Tower of Pisa (or possibly out of the university building) which were the same size, and they both landed at the same time. However, the heavier one ought to land first, and so the misunderstanding was due to insufficiently accurate measurements, and the relatively low height of the tower - if you dropped two bowling balls out of an aeroplane (one hollow, one solid), there should be a measurable difference in landing time. His result is still significant, because Aristotle had previously claimed that an object with ten times the mass would fall ten times as quickly, so the difference is far less than expected.

Disclaimer: this is all second hand information, from a site where people are arguing the results, so I could be wrong about it.

Conclusion: we ought to test this ourselves - anyone fancy lobbing water balloons off a tall building? :)
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From:totherme
Date:October 16th, 2006 04:54 pm (UTC)
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I'd expect a lead ball bearing and a lead cannonball to fall at the same speed

Likewise :)
If objects were falling in a vacuum, then I'd expect the pillowcase and paperweight to fall at the same speed, since air resistance would be irrelevant

Yup - I'd expect that too. The only one I disagreed with you on was the two equal boxes, one full of iron, the other full of feather. I expect the feather one to fall slower.


I was reading a conspiracy theory about that recently

That does sound pretty horrid doesn't it? Well, whether it's deliberately faked or not, I guess it's certainly the case that folk who volunteer for a reality TV show are a self-selecting unrepresentative sample. In the "Trading Races" programme, the emphasis of the programme was on a number of discrete experiences, so the folk who self-selected were predominantly woolly liberal. In the US show, I guess the emphasis may well be on the life and the characters, so the folk who self-select are attention-seeking.

In fact, here's an interesting "middle way" theory, to counter the conspiracy one:

The TV network want ratings. The concept is enough to get liberals to watch, so the character selection will be more profitable if they appeal to the homer simpsons of the country - with big characters. Now, imagine you're a publicity hungry small family, with a some acting experience between you all, but not enough to pay the bills - so you all have day jobs. If what you want is to act, then you understand the value of reality show publicity, and you understand what sort of characters the TV network will be after to emphasise the point of their show... How would it be best for you to behave when the cameras are around, in order to maximise your publicity?

See, the TV network doesn't need to lie at all. The families probably don't think of themselves as lying either - if they're aware of what's going on at all, they probably just think of it as a kind of selective editing, nothing more.

OTOH, that's just a theory, based on no evidence whatsoever ;)
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