Sinking in the Quicksand !!!

When I was a kid I remember watching these movies with people sinking in the sand. I guess the movie writers and the directors felt scared of the idea of quicksand and they felt obligated to warn people about it and try to give tips of how to save themselves....but unfortunately most of their information and advises are just their imagination and are not entirely correct !?!?!

In these movies, the victims are usually lost in the desert and can't find water or people and suddenly they start their journey to the center of the earth. After being halve the way there and their bodies are submerged to their chest, someone starts talking (do not ask me why they didn't talk before !) and they start advising the victim not to move at all and that if he struggles he will only sink deeper.

Africa is rich with quicksand, thus anyone thinking of visiting Africa might be thinking of this problem. That is why I need to clear out some well know mistakes about quicksand.

First fact...the quicksand is rarely found in the desert !!!

this is the first well known mistake "quicksand is found in the desert"....Wrong. Naturally, the sand is formed of small rough grains that are intervened with air or water molecules. The sand that we move on is solid because the air or water molecules intervening are not enough to completely surround each grain of sand. So the sand particles can still move against each other causing friction and this tightness and friction gives the sand its solid feeling.

So, now imaging this sand completely soaked in water and the grains are no longer in contact with one another....now the sand loses this solid feeling and turns into some sort of "gel". Thus logically quicksand needs water to develop. That is why quicksand is more around lakes, forests, river valleys or beaches. However, in the desert one can find quicksand near natural wells or near shallow underground water. So the sand can -sort of- dissolve and form the gel.

Second fact... you can't struggle...it is not a choice !!!

If the victim attempt to rise his leg upwards to try and escape -According to the laws of physics- as he elevates his leg the space below should be occupied by air or water for his leg to move up. In case of quicksand a study proved that the force needed to pull one leg out of quicksand equals to the force needed to lift a medium sized car "just to remove one leg". Because you will need a very strong suction force to pull the water from the underground to come up and replace the space that was occupied by the leg, and as there is no air coming down (remember we are talking about a gel). Thus, the scenes with victim acting like swimming in a pool are not possible.....don't you love physics !!!

Third fact...quicksand can't swallow someone completely !!!

Another physics law !!!

The human body's density is less than that of the quicksand............(1)

From (1) → if the victim stands still he will most probably float, that is correct.....(2)

Scientists studying quicksand made an artificial quicksand pit in their laboratory and they made an aluminum ball of a very high density (over that of quicksand) and placed it over the sand but it didn't reach the bottom except after shaking the pit. By shaking they caused the water to rise thus re-liquefying the sand and the ball sank....BUT...When they made another ball with lower density than that of the quicksand (just like the human body), the ball didn't sink to bottom even after vigorous shaking...........(3).

From (1), (2) and (3) you will realize that no man can actually sink completely into the quicksand even if your friend shook the earth around you instead of helping you out ...:)))

Of course, a more logic example will be...

"Someone coming to Africa for the first time and he managed to find a pit of quicksand and sank in it and a vigorous earthquake happened"

So even if that happened he will not be completely submerged and most probably he will come out alive.

But, my friend frankly no one has ever been that unfortunate and unlucky....or else...you can tell that person that this is definitely not Africa's fault and that he should do something about it !?!?!

Image credit: Quicksand Warning sign by Solipsist and the unfortunate event by The Man in Question via Wikimedia Commons.