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Heavy Boots

  1. Nov 14, 2015 #1

    pervect

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    I'd like some opinions on whether the following observation which I found on the web is legitimate. Sometimes, one sees things on the WWW that are not *gasp* on the level.

     
  2. jcsd
  3. Nov 14, 2015 #2

    phinds

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    Wouldn't surprize me at all. Depending on what poll you read something between 40% and 60% of Americans believe in ghosts, angels, and UFO aliens. The only thing that amazes me is that very few seem to believe in unicorns.
     
  4. Nov 14, 2015 #3
    I'm surprised that many of them didn't express a belief that people had never walked on the moon.

    Many people never develop a consistent worldview of physical phenomena. They simply answer questions like these as if they're riddles. Light things can fly away, but heavy things sink. Feathers can float away, but rocks can't. Scholars believed heavier things fell faster than light things. Many still do.
     
  5. Nov 15, 2015 #4

    Borg

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    Thanks for that pervect. :oldlaugh:
     
  6. Nov 15, 2015 #5

    davenn

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    I guess there were those that didn't see the hammer and feather drop that was done on the moon
     
  7. Nov 16, 2015 #6

    Ben Niehoff

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    Theoretically, if you were walking on a small enough moonlet that was spinning sufficiently fast (and made of some magical material so that it doesn't fly apart), then it is possible that releasing a pencil at shoulder height will send it into orbit, thus appearing to "float". And you would need to be wearing heavy boots in order to lower your center of gravity so that you don't float away.

    Theoretically.
     
  8. Nov 16, 2015 #7

    phinds

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    That would have to be one hell of a delicate balance to be such that lowering your center of gravity would be just enough to keep you from being flung off. Well, OK, you DID say "theoretically", so yeah, I guess. :smile:
     
  9. Nov 16, 2015 #8
    Is there any evidence that says things are floating over the moon ground? I saw Armstrong jumping up and down over there, not walking! If the gravity is small then I think there should be lots of dust around the moon's surface but there isn't. Hence the penicl should fall on the ground.
     
  10. Nov 16, 2015 #9

    phinds

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    Of course it would on our moon. That is isn't what Ben was talking about at all.
     
  11. Nov 16, 2015 #10

    mfb

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    Even ignoring the obvious logic error and the complete absence of any knowledge of physics, I wonder why heavy boots are such a frequent answer. Why specifically the boots? Why not a heavy backpack, or suit in general?

    So, out of curiosity: assume that the astronauts are on a tiny extremely dense object, rotating in such a way that a pencil, held one meter above its surface, is in orbit, while the astronauts with the very heavy boots (center of mass at the ground) feel a moon-like gravitational attraction (0.15 g). We have three degrees of freedom, so we can fix the density. The density of the moon is not sufficient, not even osmium works.
    Solutions start at a density of roughly 7kg/mm^3, or 6 orders of magnitude above the density of regular iron, similar to the density in the core of a white dwarf. Our object is not a white dwarf, however, as its radius is just a meter, and its rotational period is about 10 seconds.
     
    Last edited: Nov 16, 2015
  12. Nov 16, 2015 #11
    After a little digging I've learned this story is about old enough to drink.
    Here's the earliest reference I could find.
    I get the feeling that it is based on a true story, but like they say, "Accurate numbers aren't any more useful than the ones you make up." So I am more suspicious of the specific statistics than the story in general.
     
  13. Nov 16, 2015 #12

    Ben Niehoff

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    Well done. It reminds me of Super Mario Galaxy!
     
  14. Nov 16, 2015 #13
    Because when you see something that would otherwise float away on Earth, the heavy thing holding it down is always on the bottom.

    It's like the true-false question: Is this statement true or false?

    Those little import cars are small because they get good gas mileage.

    You'd be surprised how many people say it's true, and then when followed up declare it to be a trick question.
     
  15. Nov 16, 2015 #14
    I bet it comes from "cement overshoes."

    We know from old time gangster movies that you can't just kill someone and throw them in the water, because they'll float. The application of "cement overshoes," however, will keep the body on the bottom. It 'stands to reason' cement overshoes, or any sufficiently heavy boots, would also keep someone from floating up off the moon.
     
  16. Nov 16, 2015 #15
    I think when you see survey results like that, I really wonder if people are just picking the first thing that comes to mind within half a second in order to get it over with. I can be pretty cynical about modern society, but I have hard time believing that a large number of adults believe that, for instance, the Earth doesn't orbit the Sun, or that a pen dropped on the surface of the Moon will fall back down to Earth.

    Maybe it comes from a confusion about space and gravity. Obviously they've seen cartoons or movies where there's no gravity in space, and of course the Moon is in space, and they see videos of astronauts jumping 12 feet off the ground on the moon, so they figure "no gravity on the moon".
     
  17. Nov 17, 2015 #16
    Hahaha wow. My hope for the world is failing.
     
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