Comment Re: Revisit the quicksand myth (Score 1) 1435
I saw this episode of Mythbusters too. I'm very interested in ur alternative explanation of 'quicksand' by the mechanism of collapsing structures or voids beneath loose, fine, dry sand.. I'll check out the link soon.
But I thought I would add to this.
The 'quicksand' they tested on Mythbusters was simulated by a large plastic tank, probably about 2.5 - 3 metres in diameter & maybe 4-5 metres high.. they filled it with water and fine-medium grained sand until the mix reached a consistency that seemed like it had the 'quick' condition characteristic of quicksand, as in the movies.
Then they had a guy stand in the tank and tested whether he sunk into the quicksand. Of course, he didn't sink that far, probably up to his chest or so, and they concluded that quicksand does not exist.
'Quicksand' in a natural environment would exist in a swampy, marsh or jungle setting.. in that sort of environment, the soils contain a lot of silt which are very fine particles (2-70 microns?)and when combined with water, have a very slippery texture. The upper materials would be mostly leaves and organic matter & topsoil.
A swampy area like this is also not contained in a small tank like on Mythbusters, which in effect prevented the man from sinking. The sand around the guy was displaced sideways and compressed into the tank walls. This compressive horizontal force, when combined with the natural upwards buoyancy force of the water, would have stopped him from sinking to the bottom.
If they want to test it properly, they need to have a large open space, or at least a very large diameter tank, with gradually sloped walls, so that no significant sideways force can stop them from sinking.
They should also try different mixtures of clays, silts, sands and organic materials more characterstic of a swampy quicksand.
Of course, the tank was a nice start to show these things, but I really wish they wouldn't just draw conclusions without refining their models and thinking more carefully about the actual mechanisms at work in some of these 'myths'.
But I thought I would add to this.
The 'quicksand' they tested on Mythbusters was simulated by a large plastic tank, probably about 2.5 - 3 metres in diameter & maybe 4-5 metres high.. they filled it with water and fine-medium grained sand until the mix reached a consistency that seemed like it had the 'quick' condition characteristic of quicksand, as in the movies.
Then they had a guy stand in the tank and tested whether he sunk into the quicksand. Of course, he didn't sink that far, probably up to his chest or so, and they concluded that quicksand does not exist.
'Quicksand' in a natural environment would exist in a swampy, marsh or jungle setting.. in that sort of environment, the soils contain a lot of silt which are very fine particles (2-70 microns?)and when combined with water, have a very slippery texture. The upper materials would be mostly leaves and organic matter & topsoil.
A swampy area like this is also not contained in a small tank like on Mythbusters, which in effect prevented the man from sinking. The sand around the guy was displaced sideways and compressed into the tank walls. This compressive horizontal force, when combined with the natural upwards buoyancy force of the water, would have stopped him from sinking to the bottom.
If they want to test it properly, they need to have a large open space, or at least a very large diameter tank, with gradually sloped walls, so that no significant sideways force can stop them from sinking.
They should also try different mixtures of clays, silts, sands and organic materials more characterstic of a swampy quicksand.
Of course, the tank was a nice start to show these things, but I really wish they wouldn't just draw conclusions without refining their models and thinking more carefully about the actual mechanisms at work in some of these 'myths'.
