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#1 2006-08-06 05:08:39

Devantè
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Registered: 2006-07-14
Posts: 6,400

Death by Quicksand - Is It Possible?

Once again, the Mythbusters set out to try and prove that you cannot die from sinking in quicksand.

First, the Mythbusters experimented with one of their team members in ordinary sand, mud, and fine-grained sand. They proved that the fine-grained sand was best for their testing. It was capable of sinking (slightly) a human being, but only up to the shins. But the Mythbusters weren't pleased with that - They wanted real quicksand - Fine-grained quicksand. It someone up to the chest, but strangely enough, the quicksand stopped sinking the human. The human could easily escape, and he was buoyant, meaning he could easily climb out of the quicksand. The Mythbusters were puzzled, so they tried again. And again. And again. But no matter how hard they tried, the human always remained buoyant, and was never able to reach the bottom, and be covered completely in the quicksand. They tried pushing down on the human, but no - Because of the human's outstanding buoyancy, he just bounced back up again.

Thus, the Mythbusters proved that there is no way to drown from quicksand. It could drag you down, yes, but only up until the chest.

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#2 2006-08-06 07:33:02

Ricky
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Registered: 2005-12-04
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Re: Death by Quicksand - Is It Possible?

Again, no proof here.  Sure, they tried a couple of different tests with different types of quicksand which provides a good basis of evidence, but did they try them all?  No.

But there is no need for tests.  A little physics and common sense is all it takes.  Do humans float in water?  Yes.  Does adding sand to water make the sand/water mixture more dense?  Yes.  Do humans float better or worse is a more dense mixture?  Better.  Thus, you can't drown in quicksand.


"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

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#3 2006-08-06 09:49:58

MathsIsFun
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Registered: 2005-01-21
Posts: 7,535

Re: Death by Quicksand - Is It Possible?

It fascinated me ... I was under the delusion that you would be sucked down (I never thought to think about it, really).


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#4 2006-09-01 05:50:53

Devantè
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Registered: 2006-07-14
Posts: 6,400

Re: Death by Quicksand - Is It Possible?

Neither did I. Sometimes we just forget what the myth is really talking about, and how it relates to fact and fiction.

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#5 2006-09-01 07:00:50

mathsyperson
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Registered: 2005-06-22
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Re: Death by Quicksand - Is It Possible?

But isn't the reason people drown in quicksand because they move when they're in it?
Yes, if they stayed perfectly still then their weight and their buoyancy would find an equilibrium and they'd eventually float from their chest up. But, the majority of people who find themselves in quicksand would most probably flail about in panic, which would disrupt the equilibrium and maybe cause them to sink further?

Another thing to think about is that if people do stay still and stay floating from the chest up, would they be able to breathe properly? A sand-water mix would probably be quite restrictive on the movement of your lungs.


Why did the vector cross the road?
It wanted to be normal.

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#6 2006-09-01 10:13:50

MathsIsFun
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Re: Death by Quicksand - Is It Possible?

I imagine the "myth" came about because you *do* seem to sink, and people freak out and get "ashore" before they discover they were perfectly safe.

On the other hand - it may be possible to get stuck, like a horse in the mud, and perish there.


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#7 2006-09-01 11:21:58

Ricky
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Re: Death by Quicksand - Is It Possible?

A sand-water mix would probably be quite restrictive on the movement of your lungs.

Your rib cage does expand when you breath.  Pressure upon it makes it so that you can't expand your chest.  If you are floating chest up, then your chest is very near or above the top of the quicksand.  This means that there is very little weight, and thus, very little pressure upon your chest.

Haven't you ever been buried in wet sand at the beach? tongue


"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

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#8 2006-09-01 18:37:27

justlookingforthemoment
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Registered: 2005-05-26
Posts: 2,161

Re: Death by Quicksand - Is It Possible?

Ricky wrote:

Haven't you ever been buried in wet sand at the beach?

Yes.

I thought it was a big mound of dry sand I was jumping into, but actually, it was a large pile of wet muddy sand. You can imagine what happened.

And then there was the time I was wearing thongs on the beach and they got suctioned into the sand ...

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#9 2006-09-01 19:02:24

Zhylliolom
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Registered: 2005-09-05
Posts: 412

Re: Death by Quicksand - Is It Possible?

Tell us more, justlookingforthemoment.

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#10 2006-09-01 19:21:28

ryos
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Registered: 2005-08-04
Posts: 394

Re: Death by Quicksand - Is It Possible?

The maximum pressure your lungs can withstand and still breathe is determined by the strength of your diaphragm. I wonder how much "weight" this little muscle can lift? After all, it never gets a rest; it's always working.

If you're curious as to why scuba divers are able to withstand the pressures of the deep, it's because they are breathing from a pressurized tank. The regulator (mouthpiece) matches the pressure of the air they breathe to the pressure of the water outside (the "atmosphere"), so the balance is maintained and the diaphragm doesn't have to do any extra work. Breathing with a SCUBA feels just like breathing at the surface.

A standard scuba tank holds 3000psi of air. That pressure isn't matched until you get to a depth of about 7125 ft. Of course, at that depth you'd use up your whole 3000psi tank in 3 or 4 breaths. You'd also have a lot of other issues to deal with...

Sorry to go OT; I just love scuba diving. smile


El que pega primero pega dos veces.

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#11 2006-09-01 19:36:09

Ricky
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Posts: 3,791

Re: Death by Quicksand - Is It Possible?

You just have to be careful when diving.  You can be under a lot of pressure.  Almost all of the time you get in over your head.  And I hate to burst your bubble, but when you only go 30 feet deep, you're just getting your feet wet.


"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

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#12 2006-09-24 06:07:01

elite-mathlete
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Registered: 2006-07-16
Posts: 40

Re: Death by Quicksand - Is It Possible?

this has been tried with custard as well. if you fill a pool with custard, and run across it, you won't sink an inch, but stay still, and it'll make you sink. If you try to get out of it, it'll pull you back in. custard, when being affected by motion, will turn into a solid, but when standing still, it will act like a liquid. thus if you stand in custard, you will sink, but you can run across it too, because your running is affecting it with motion.


Maybe the helicopter, maybe it's made of chocolate.

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#13 2006-09-24 06:26:18

luca-deltodesco
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Registered: 2006-05-05
Posts: 1,470

Re: Death by Quicksand - Is It Possible?

its called viscosity elite-mathlete, viscosity is the measure of a fluids resistance to deform under shear force.

glass is an example of a fluid with an extremely high viscosity, (yes glass is NOT a solid, but a fluid)
quicksand, custard are examples of fluids with an obvious extreme less viscosity, but high enough to give resistance.

its like friction, as the force against the fluid increases, the frictional force increases exponentialy, so apply a small force to the fluid, and you get very little resistance, but apply a large force, and you get an extremely high resistance, the reason why standing still, you would sink, but if you try to move quickly to get out, it feels like a solid, and stops you moving, similarly when walking/running on the custard in braniac, you apply a large force to the fluid, and it gives a large resistance back, enough to let you walk on it

there is even a creature, a small spider, than runs extremely fast, with very powerful legs and a very light body, that can run accross water because of the resistance to deform.

Last edited by luca-deltodesco (2006-09-24 06:29:23)


The Beginning Of All Things To End.
The End Of All Things To Come.

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#14 2006-09-24 08:09:45

mathsyperson
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Registered: 2005-06-22
Posts: 4,900

Re: Death by Quicksand - Is It Possible?

That spider doesn't use viscosity to do that though. If that was the case then it would sink when it stopped, but it can be stationary on the water and still float. Instead, it relies on the fact that its weight isn't enough to break the surface tension.

There are other creatures that can run across water in that way though. Some lizards can, for example.


Why did the vector cross the road?
It wanted to be normal.

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#15 2006-09-24 12:55:34

elite-mathlete
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Registered: 2006-07-16
Posts: 40

Re: Death by Quicksand - Is It Possible?

Oh yes, now I remember. Viscosity. I learned about that last year in 9th grade. Thanks for reminding me.


Maybe the helicopter, maybe it's made of chocolate.

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#16 2006-09-24 18:43:24

luca-deltodesco
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Registered: 2006-05-05
Posts: 1,470

Re: Death by Quicksand - Is It Possible?

mathsyperson wrote:

That spider doesn't use viscosity to do that though. If that was the case then it would sink when it stopped, but it can be stationary on the water and still float. Instead, it relies on the fact that its weight isn't enough to break the surface tension.

There are other creatures that can run across water in that way though. Some lizards can, for example.

ah well tongue, i thought that was the case, not that it wouldnt be possible though.


The Beginning Of All Things To End.
The End Of All Things To Come.

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#17 2006-09-25 11:22:29

randompasserby
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Registered: 2006-09-25
Posts: 3

Re: Death by Quicksand - Is It Possible?

I heard that if you lie on your back in quicksand you cant sink. Is that really the case??

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#18 2006-09-26 12:45:22

elite-mathlete
Member
Registered: 2006-07-16
Posts: 40

Re: Death by Quicksand - Is It Possible?

don't know, don't wanna try.


Maybe the helicopter, maybe it's made of chocolate.

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#19 2006-09-26 12:53:20

justlookingforthemoment
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Registered: 2005-05-26
Posts: 2,161

Re: Death by Quicksand - Is It Possible?

randompasserby wrote:

I heard that if you lie on your back in quicksand you cant sink. Is that really the case??

This says that 'If you are sinking beyond your thighs, lie back and distribute your weight evenly over the surface. Don't lean forward or try to crawl or "swim" out unless you are in really  deep! In thicker mud and quicksand, this will only work you in further. Lying back causes you to "backfloat" so that you can slowly and carefully pull your legs free. Once the legs are out, roll over the top and onto firm ground.'

So, I think lying on your back doesn't make you unsinkable, but it might help get you out of sticky situations.

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#20 2006-09-27 03:48:20

ryos
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Registered: 2005-08-04
Posts: 394

Re: Death by Quicksand - Is It Possible?

I personally can float on my back in ordinary water. I would imagine quicksand would be the same.


El que pega primero pega dos veces.

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