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Quicksand

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grizzly
208771.  Tue Sep 11, 2007 3:21 pm Reply with quote

Q. What happens to you if you sink into quicksand?

K. Sink below the surface and drown.

Answer:

Just like water, quicksand is denser than a human body so a person will naturally float on quicksand. Indeed with the significant volume of sand suspended in the water it is considerably denser than water. Consequently a person standing upright would struggle to sink below their waist.

The danger of quicksand mainly comes from the fact that it is a non-newtonian fluid (discussed on the show with reference walking on custard in the C series). Applying any pressure to it will cause it to solidify (hence why you can also walk on custard) so if you stand still long enough you can sink in too far to lift yourself out. Hence the majority of drownings cause by quicksand occur in tidal estuaries where people become trapped and then drown when the tide comes in.

Ref: Great British Journeys on BBC2. Repeated on BBC2 this Thursday at 7:00pm.

 
Flash
208826.  Tue Sep 11, 2007 5:03 pm Reply with quote

post 17535

 
Curious Danny
209007.  Wed Sep 12, 2007 10:13 am Reply with quote

Quicksand is deadly if you aren't careful.

Fill up a bucket with wet sand when the tide is out and sink your hand into it. You will find, compared to water, it is suprisingly difficult to pull out.

When you sink into quicksand up to your waist it is very difficult to pull yourself out. Which is why when children digging holes on the beach find themselves half-buried, it is a race against time to dig them out. Pulling them out isn't advisable as it is possible to damage their arms.

 
mckeonj
209050.  Wed Sep 12, 2007 11:18 am Reply with quote

I can see the saucy postcard now:
"What have you done to my little Willy?"

 
Bondee
209083.  Wed Sep 12, 2007 11:50 am Reply with quote

grizzly wrote:
Q. What happens to you if you sink into quicksand?

K. Sink below the surface and drown.

Answer:

Just like water, quicksand is denser than a human body so a person will naturally float on quicksand. Indeed with the significant volume of sand suspended in the water it is considerably denser than water. Consequently a person standing upright would struggle to sink below their waist.

The danger of quicksand mainly comes from the fact that it is a non-newtonian fluid (discussed on the show with reference walking on custard in the C series). Applying any pressure to it will cause it to solidify (hence why you can also walk on custard) so if you stand still long enough you can sink in too far to lift yourself out. Hence the majority of drownings cause by quicksand occur in tidal estuaries where people become trapped and then drown when the tide comes in.


We were told exactly the same thing by Cedric Robinson, the Queens Guide to The Sands, on the walk across the Morecambe Bay last Saturday.

 
Lumpo31
209107.  Wed Sep 12, 2007 2:05 pm Reply with quote

grizzly wrote:

Ref: Great British Journeys on BBC2. Repeated on BBC2 this Thursday at 7:00pm.


Blast! I was just going to write, "Were you inspired to this because of Nick Crane's programme?"

He's absolutely brilliant, by the way. I love him in everything he does. Beg, borrow or steal a copy of Nick's "Clear Waters Rising: A Mountain Walk Across Europe". He's truly a class act and it's a fabulous read.

Lisa

 
mr2mk1g
209126.  Wed Sep 12, 2007 5:04 pm Reply with quote

Anyone who watches Discovery Channel's Myth Busters will be familiar with full scale experiment's relating to this one.

The two presenters created an 8ft across by 20ft high (my estimations from memory) vat of sand and blasted water through it via specially designed ports all round the lower sides with overflow ports round the upper sides.

The result frankly, was a pretty good facsimile of naturally occurring quicksand.

Their tests demonstrated the buoyancy of quicksand. The presenters floated in the quicksand at mid-thigh height. That in its self was quite a sight - you really don't expect to see someone floating in a liquid that high. They demonstrated the affect when one presenter pushed down on the head of the other - they nearly fully submerged but when released bobbed back to the surface like a cork.

The show's conclusion was that the whole quicksand received logic was an absolute myth. I don't really have any issues with their conclusions.

 
smiley_face
209146.  Wed Sep 12, 2007 6:08 pm Reply with quote

The most endearing thing about Nick Crane has to be the umbrella that pokes out of the top of his bag.

 
dr.bob
209160.  Thu Sep 13, 2007 3:10 am Reply with quote

mr2mk1g wrote:
The show's conclusion was that the whole quicksand received logic was an absolute myth. I don't really have any issues with their conclusions.


I thought the received logic with quicksand was that, if you struggle, you will hasten your demise. If, however, you relax, lie flat, and move slowly at all times, you can extricate yourself relatively easily.

This sounds like it would tie in with quicksand being thixotropic.

 
Flash
209175.  Thu Sep 13, 2007 4:21 am Reply with quote

Quicksand, piranhas and nitroglycerine all have conventional attributes for film-makers, attributes that audiences understand and subscribe to willingly, I think.

 
npower1
209177.  Thu Sep 13, 2007 4:33 am Reply with quote

Thixotropic,

What a wonderful new word.

My spell check dictionary doesn't recognise it.

Doing a Google search leads where exactly? All Google searches can lead to infinite Google time.

Why this mystical writing?

Google thixotropic13.

 

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